Robert J. Henning

Vasoactive intestinal peptide: cardiovascular effects

Vasoactive intestinal peptide (VIP) is present in the peripheral and the central nervous systems where it functions as a nonadrenergic, noncholinergic neurotransmitter or neuromodulator. Significant concentrations of VIP are present in the gastrointestinal tract, heart, lungs, thyroid, kidney, urinary bladder, genital organs and the brain. On a molar basis, VIP is 50-100 times more potent than acetylcholine as a vasodilator. VIP release in the body is stimulated by high frequency (10-20 Hz) nerve stimulation and by cholinergic agonists, serotonin, dopaminergic agonists, prostaglandins (PGE, PGD), and nerve growth factor. The VIP peptide combines with its receptor and dose-dependently activates adenylyl cyclase. The vasodilatory effect of VIP in different vascular tissues or species also may be due to increases in nitric oxide, cyclic GMP, and other signaling agents. In the heart, VIP immunoreactive nerve fibers are present not only in the epicardial coronary arteries and veins, but also the sinoatrial node, atrium, interatrial septum, atrioventricular node, intracardiac ganglia, and ventricles (right ventricle >> left ventricle). In the coronary arterial walls, VIP may contribute to the regulation of normal coronary vasomotor tone. In research animals and in humans, VIP, administered into the coronary artery or intravenously, increases the epicardial coronary artery cross-sectional area, decreases coronary vascular resistance, and significantly increases coronary artery blood flow. High frequency parasympathetic (vagal) nerve stimulation also releases endogenous VIP in the coronary vessels and heart and significantly increases coronary artery blood flow. In addition, the release of VIP in the heart is increased during coronary artery occlusion and during reperfusion where VIP may promote local blood flow and may have a free-radical scavenging effect. VIP also has a primary positive inotropic effect on cardiac muscle that is enhanced by its ability to facilitate ventricular-vascular coupling by reducing mean arterial pressure by 10-15%. In concentrations of 10(-8)-10(-5) mol, VIP augments developed isometric force and increases atrial and ventricular contractility. The presence of VIP-immunoreactive nerve fibers in and around the sinus and the atrioventricular nodes of mammals strongly suggests that this peptide can affect the heart rate. In this regard, endogenously released or exogenous VIP can significantly increase the heart rate and has a more potent effect on heart rate than does norepinephrine. The presence and significant cardiovascular effects of VIP in the heart suggests that this peptide is important in the regulation of coronary blood flow, cardiac contraction, and heart rate. Current investigations are defining the physiological role of VIP in the regulation of cardiovascular function.

Human umbilical cord blood mononuclear cells for the treatment of acute myocardial infarction.

Cell transplantation is a new treatment to improve cardiac function in hearts that have been damaged by myocardial infarction. We have investigated the use of human umbilical cord blood mononuclear progenitor cells (HUCBC) for the treatment of acute myocardial infarction. The control group consisted of 24 normal rats with no interventions. The infarct + vehicle group consisted of 33 rats that underwent left anterior descending coronary artery (LAD) ligation and after 1 h were given Isolyte in the border of the infarction. The infarct + HUCBC group consisted of 38 rats that underwent LAD ligation and after 1 h were given 106 HUCBC in Isolyte directly into the infarct border. Immunosuppression was not given to any rat. Measurements of left ventricular (LV) ejection fraction, LV pressure, dP/dt, and infarct size were determined at baseline and 1, 2, 3, and 4 months. The ejection fraction in the controls decreased from 88 ± 3% to 78 ± 4% at 4 months (p = 0.03) as a result of normal aging. Following infarction in the infarct + vehicle group, the ejection fraction decreased from 87 ± 4% to 51 ± 3% between 1 and 4 months (p < 0.01). In contrast, the ejection fraction of the infarcted + HUCBC-treated rat hearts decreased from 87 ± 4% to 63 ± 3% at 1 month, but progressively increased to 69 ± 6% at 3 and 4 months, which was different from infarct + vehicle group rats (p < 0.02) but similar to the controls. At 4 months, anteroseptal wall thickening in infarct + HUCBC group was 57.9 ± 11.6%, which was nearly identical to the control anteroseptal thickening of 59.2 ± 8.9%, but was significantly greater than the infarct + vehicle group, which was 27.8 ± 7% (p < 0.02). dP/dtmax increased by 130% in controls with 5.0 μg of phenylephrine (PE)/min (p < 0.001). In the infarct + vehicle group, dP/dtmax increased by 91% with PE (p = 0.01). In contrast, in the infarct + HUCBC group, dP/dtmax increased with PE by 182% (p < 0.001), which was significantly greater than the increase in dP/dtmax in the infarct + vehicle group (p = 0.03) and similar to the increase in the controls. Infarct sizes in the infarct + HUCBC group were smaller than the infarct + vehicle group and averaged 3.0 ± 2.8% for the infarct + HUCBC group versus 22.1 ± 5.6% for infarct + vehicle group at 3 months (p < 0.01); at 4 months they averaged 9.2 ± 2.0% for infarct + HUCBC group versus 40.0 ± 9.2% for the infarct + vehicle group (p < 0.001). The present experiments demonstrate that HUCBC substantially reduce infarction size in rats without requirements for immunosuppression. As a consequence, LV function measurements, determined by LV ejection fraction, wall thickening, and dP/dt, are significantly greater than the same measurements in rats with untreated infarctions.

Cocaine: Pathophysiology and clinical toxicology

PURPOSE To review the medical complications of cocaine abuse and the mechanisms of action of cocaine that contribute to medical complications. DATA SOURCES Pertinent articles identified through a MEDLINE search of the English-language literature from 1985 to 1996 and through a manual search of bibliographies of all identified articles. STUDY SELECTION All articles describing complications of cocaine use including case reports, small reported series, and review articles. DATA SYNTHESIS A qualitative description of reported complications. RESULTS Since the introduction of freebase and crack cocaine, multiple medical complications have been observed, and all major body organ systems have been affected. Cocaine can cause acute strokes, myocardial infarction, cardiac dysrhythmias, pulmonary edema, rhabdomyolysis, and acute renal failure. CONCLUSION Adverse reactions to cocaine should be considered in the differential diagnosis of acute ischemic events that occur in young adults. General awareness of the significant complications of cocaine will facilitate early diagnosis and prompt treatment.

Vagal nerve stimulation releases vasoactive intestinal peptide which significantly increases coronary artery blood flow

OBJECTIVE To determine the effects of vasoactive intestinal peptide (VIP), released endogenously from cardiac vagal nerves, on coronary artery blood flow (CBF). METHODS We determined the effects of vagal nerve stimulation (VNS) at frequencies of 10, 15, 20, and 30 Hz on left circumflex coronary artery (LCx) blood flow. The increases in CBF during VNS were compared with the increases in CBF produced by exogenous VIP and also nitroglycerin (NTG). In 18 anesthetized open chest mongrel dogs, we blocked the muscarinic and beta-adrenergic receptors with atropine and propranolol. We controlled heart rate and aortic pressure by right atrial pacing and an arterial reservoir. CBF was measured in the LCx with a Doppler flow probe. A 25 gauge catheter was placed in the proximal LCx to inject the VIP receptor antagonist [4Cl-D-Phe6Leu17]VIP, VIP, NTG, or vehicle. CBF, aortic and ventricular pressures, ventricular contractility (+dp/dt(max)) and relaxation (-dp/dt(min)) and the EKG were measured. RESULTS VNS (0.5 ms, 20 V, 5 min.) at 20 Hz maximally increased CBF by 62 +/- 14% at 5 min from 71 +/- 10 to 115 +/- 19 ml/min (p < 0.01). VNS at 10, 15, and 30 Hz increased CBF by 6 +/- 1%, 24 +/- 5%, and 24 +/- 7%, respectively (all p < 0.05 vs control). Following 20 Hz VNS, CBF returned toward the baseline over 30 min. Aortic and left ventricular (LV) pressures, LV +dp/dt(max) and LV-dp/dt(min) did not significantly change. After the direct administration of [4Cl-D-Phe6Leu17]VIP into the LCx, VNS increased CBF by only 10 +/- 4% (p = NS). Exogenous VIP, in doses of 9.0 x 10(-11) to 2.1 x 10(-9) mol, increased CBF by 106 +/- 17% to 169 +/- 17% (all p < 0.01 vs control). NTG, in doses of 2.2 x 10(-8) to 1.7 x 10(-7) mol, increased CBF by 101 +/- 15% to 169 +/- 20% (all p < 0.01 vs control). These increases in CBF persisted during the 1 to 2 min injection period and returned to the baseline within 5 min. Neither VIP nor NTG significantly changed the heart rate, aortic or LV pressures, LV +dp/dt(max) or LV -dp/dt(min). VNS at 20 Hz, exogenous VIP, 9.0 x 10(-11) mol, and exogenous NTG, 2.2 x 10(-8) to 4.4 x 10(-8) mol, produced equivalent increases in CBF by analysis of variance determination. CONCLUSION The present experiments suggest that VNS releases VIP which directly dilates coronary arteries and significantly increases coronary artery blood flow.

Human cord blood cells and myocardial infarction: effect of dose and route of administration on infarct size.

There is no consensus regarding the optimal dose of stem cells or the optimal route of administration for the treatment of acute myocardial infarction. Bone marrow cells, containing hematopoietic and mesenchymal stem cells, in doses of 0.5 × 106 to >30 × 106 have been directly injected into the myocardium or into coronary arteries or infused intravenously in subjects with myocardial infarctions to reduce infarct size and improve heart function. Therefore, we determined the specific effects of different doses of human umbilical cord blood mononuclear cells (HUCBC), which contain hematopoietic and mesenchymal stem cells, on infarct size. In order to determine the optimal technique for stem cell administration, HUCBC were injected directly into the myocardium (IM), or into the LV cavity with the ascending aorta transiently clamped to facilitate coronary artery perfusion (IA), or injected intravenously (IV) in rats 1–2 h after the left anterior coronary artery was permanently ligated. Immune suppressive therapy was not given to any rat. One month later, the infarct size in control rat hearts treated with only Isolyte averaged 23.7 ± 1.7% of the LV muscle area. Intramyocardial injection of HUCBC reduced the infarct size by 71% with 0.5 × 106 HUCBC and by 93% with 4 × 106 HUCBC in comparison with the controls (p < 0. 001). Intracoronary injection reduced the infarction size by 47% with 0.5 × 106 HUCBC and by 80% with 4 × 106 HUCBC (p < 0. 001), and IV HUCBC reduced infarct size by 51% with 0.5 × 106 and by 75–77% with 16–32 million HUCBC (p < 0. 001) in comparison with control hearts. With 4 × 106 HUCBC, infarction size was 65% smaller with IM HUCBC than with IA HUCBC and 78% smaller than with IV HUCBC (p < 0. 05). Nevertheless, IM, IA, and IV HUCBC all produced significant reductions in infarct size in comparison with Isolyte-treated infarcted hearts without requirements for host immune suppression. The present experiments demonstrate that the optimal dose of HUCBC for reduction of infarct size in the rat is 4 × 106 IM, 4 × 106 IA, and 16 × 106 IV, and that the IM injection of HUCBC is the most effective technique for reduction in infarct size.

Human umbilical cord blood progenitor cells are attracted to infarcted myocardium and significantly reduce myocardial infarction size.

We are investigating the effects of human umbilical cord blood mononuclear progenitor cells (HUCBC) for the treatment of acute myocardial infarction because human cord blood is a readily available and an abundant source of primitive cells that may be beneficial in myocardial repair. However, there is currently no scientific consensus on precisely when to inject stem/progenitor cells for the optimal treatment of acute myocardial infarction. We used an in vitro assay to determine the attraction of infarcted rat myocardium at 1, 2, 2.5, 3, 6, 12, 24, 48, and 96 h after left anterior descending coronary artery (LAD) occlusion from 45 rats for HUCBC in order to determine the optimal time to transplant HUCBC after myocardial infarction. Our assay is based on the migration of fluorescent DAPI-labeled HUCBC from wells in an upper chamber of a modified Boyden apparatus through a semiporous polycarbonate membrane into wells in a lower chamber that contain either normal or infarcted myocardium. DAPI-labeled HUCBC (100,000) were placed in each of the separate wells above the membrane that corresponded to normal or infarct homogenate in the lower wells. The greatest HUCBC migration to infarcted myocardium occurred at 2 h and 24 h after LAD occlusion in comparison with normal controls. A total of 76,331 ± 3384 HUCBC migrated to infarcted myocardium at 2 h and 69,911 ±2732 at 24 h after LAD occlusion (both p < 0.001) and significantly exceeded HUCBC migration to normal heart homogenate. The HUCBC migration remained greatest at 2 and 24 h after LAD occlusion when the number of migrated cells was adjusted for the size of each myocardial infarction. Injection of 106 HUCBC in saline into infarcted myocardium of non immunosuppressed rats within 2 h (n = 10) or at 24 h (n = 5) after LAD occlusion resulted in infarction sizes 1 month later of 6.4 ± 0.01% and 8.4 ± 0.02% of the total left ventricular muscle area, respectively, in comparison with infarction sizes of 24.5 ± 0.02% (n = 10) in infarcted rat hearts treated with only saline (p < 0.005). Acute myocardial infarction in rats treated with only saline increased the myocardial concentration of tumor necrosis factor-α (TNF-α) from 6.9 ± 0.8% to 51.3 ± 4.6%, monocyte/macrophage chemoattractant protein (MCP-1) from 10.5 ± 1.1% to 39.2 ± 2.0%, monocyte inflammatory protein (MIP) from 10.6± 1.6% to 23.1 ± 1.5%, and interferon-? (INF-?) from 8.9 ± 0.3% to 25.0 ± 1.7% between 2 and 12 h after coronary occlusion in comparison with known controls (all p < 0.001). In contrast, the myocardial concentrations of these cytokines in rat hearts treated with HUCBC did not significantly change from the controls at 2, 6, 12, and 24 h after coronary occlusion. The present investigations suggest that infarcted myocardium significantly attracts HUCBC, that HUCBC can substantially reduce myocardial infarction size, and that HUCBC can limit the expression of TNF-α, MCP-1, MIP, and INF-? in acutely infarcted myocardium.

Human Cord Blood Mononuclear Cells Decrease Cytokines and Inflammatory Cells in Acute Myocardial Infarction

We investigated whether human umbilical cord blood mononuclear cells (HUCBC), which contain hematopoietic and mesenchymal progenitor cells, can limit myocardial cytokine expression and inflammatory cell infiltration in acute myocardial infarction. We permanently ligated the left coronary artery of rats and injected into the myocardium either Isolyte or 4 x 10(6) HUCBC in Isolyte and measured myocardial cytokines with antibody arrays at 2, 6, 12, 24, and 72 hours after infarction. We then measured with flow cytometry myocardial macrophages, neutrophils and lymphocytes at 12, 24, and 72 hours after infarctions in rats treated with either intramyocardial Isolyte or 4 x 10(6) HUCBC. In the Isolyte-treated hearts, between 2 and 12 hours after myocardial infarction, tumor necrosis factor-alpha increased from 6.7 +/- 0.9% to 52.3 +/- 4.7%, monocyte chemoattract protein increased from 9.5 +/- 1.2% to 39.8 +/- 2.1%, fractalkine increased from 11 +/- 1.5% to 28.1 +/- 1.3%, ciliary neurotrophic factor increased from 12.1 +/- 0.02% to 25.9 +/- 1.1%, macrophage inflammatory protein increased from 10.3 +/- 1.5% to 23.9.0 +/- 1.4%, interferon-gamma increased from 8.7 +/- 0.4% to 26.0 +/- 1.6%, interleukin-1beta increased from 6.1 +/- 0.04% to 19.0 +/- 1.2%, and IL-4 increased from 5.9 +/- 0.03% to 15 +/- 1.5% (all p < 0.001 compared with controls). The concentrations of fractalkine remained significantly increased at 72 hours after acute infarction. In contrast, the myocardial concentrations of these cytokines did not significantly change in HUCBC treated hearts at 2, 6, 12, 24, or 72 hours after infarction. The percentage of neutrophils increased from 0.04 +/- 0.2%/50,000 heart cells in the controls to 5.3 +/- 1.2%/50,000 heart cells 12 hours after infarction in Isolyte-treated hearts but averaged only 1.3 +/- 0.7%/50,000 heart cells in HUCBC treated hearts (p < 0.02). Thereafter, the percentages of neutrophils rapidly decreased at 24 and at 72 hours after infarction and averaged 0.6 +/- 0.2%/50,000 heart cells at 72 hours after infarction in Isolyte-treated hearts in contrast to 0.2 +/- 0.1%/50,000 cells in HUCBC hearts (p < 0.05). Moreover, the percentages of neutrophils at 24 and 72 hours in HUCBC hearts were not significantly different from controls. At 24 hours post infarction, the percentage of CD3 and CD4 lymphocytes were 10.7 +/- 1.4% and 6.3 +/- 1.1%/50,000 cells in Isolyte hearts in comparison with only 4.9 +/- 0.8% and 2.9 +/- 0.5% in HUCBC hearts (p < 0.005 for Isolyte versus HUCBC). The percentage of CD11b macrophages was 2.8 +/- 0.3% in Isolyte hearts and 1.9 +/- 0.2% in HUCBC treated hearts (p < 0.05). At 72 hours after infarction, the percentage of CD3 and CD4 lymphocytes averaged 8.0 +/- 1.1% and 5.1 +/- 0.8%/50,000 heart cells in Isolyte hearts in comparison with only 4.1 +/- 0.5% and 2.3 +/- 0.4%/50,000 heart cells in the HUCBC treated infarctions (p < 0.005). Left ventricular infarct sizes in Isolyte-treated hearts at 72 hours post infarction averaged 15.7 +/- 1.4% of the left ventricular muscle area in contrast to HUCBC treated infarctions that averaged 6.9 +/- 1.4% of the left ventricular muscle area (p < 0.02). Moreover in rats followed for 2 months post infarction, the LV ejection fractions decreased to 65.4 +/- 1.9% and 69.1 +/- 1.9% at 1 and 2 months after infarction in Isolyte-treated hearts and were significantly different from HUCBC treated hearts that averaged 72.1 +/- 1.3% and 75.7 +/- 1.4% (both p < 0.02). The present experiments suggest that an important mechanism whereby HUCBC limit infarct size and improve left ventricular ejection fraction is by significantly limiting inflammatory cytokines and inflammatory cells in infarcted myocardium.

Cocaethylene is as cardiotoxic as cocaine but is less toxic than cocaine plus ethanol.

Cocaethylene is a pharmacologically active cocaine metabolite that is produced in the liver by the transesterification of cocaine only in the presence of ethanol. The acute cardiovascular effects of cocaethylene are not known. We compared the acute cardiovascular effects of cocaethylene with cocaine and with cocaine plus ethanol in 18 dogs. We administered cocaethylene 7.5 mg/kg to 6 dogs, cocaine 7.5 mg/kg to 6 dogs, and cocaine 7.5 mg/kg plus ethanol 1 gm/kg to 6 dogs. The dose of each drug was chosen to produce in dogs the concentrations of cocaethylene or cocaine that have been measured in patients who have experienced cardiotoxic reactions to cocaine or cocaine plus ethanol. Arterial, left ventricular (LV), pulmonary artery wedge pressures (PAWP), the maximum rate of LV pressure rise [(dP/dt)max] and fall [(dP/dt)min], and heart rate (HR) were continuously measured. Stroke volume was determined 3 times during the first hour after drug administration then hourly for four hours. The concentrations of cocaethylene and cocaine peaked in the serum at 3717 +/- 651 ng/ml and 4140 +/- 459 ng/ml, respectively, two minutes after each bolus. The median half-life of cocaethylene was 144.3 minutes whereas the median half-life of cocaine was 96.7 minutes (p < 0.01). Cocaethylene maximally decreased (dP/dt)max by 44%, (dP/dt)min by 29%, and stroke volume by 28% (all p < 0.01) and increased the PAWP by 50% (p < 0.02) and the HR by 13% (p = NS) during the first hour. Cocaine maximally decreased (dP/dt)max by 40%, (dP/dt)min by 31%, and the stroke volume by 26% and increased the PAWP by 100% and the HR by 46% (all p < 0.01) during the first hour. Ethanol plus cocaine maximally decreased (dP/dt)max by 68%, (dP/dt)min by 78% and the stroke volume by 49% and increased the PAWP by 118% and the HR by 74% (all p < 0.01) during the first hour. In this last group, (dP/dt)max and stroke volume remained depressed by approximately 20% (p < 0.01) for five hours. We conclude that cocaethylene is as toxic as cocaine to the myocardium but is less toxic than ethanol plus cocaine.

Cocaine activates calcium/calmodulin kinase II and causes cardiomyocyte hypertrophy.

Cardiac hypertrophy occurs in as many as 47% of normotensive individuals who chronically use cocaine. We investigated the effects of cocaine, in concentrations commonly found in chronic cocaine users, on calcium/calmodulin kinase (CaMK), and whether cocaine can activate CaMK, increase cardiac myocyte protein expression, and cause cardiac hypertrophy in this manner. In series I to III, 0 (control) or cocaine in concentrations of 10−8 to 10−5 mol/L was added to cultured adult rat cardiac ventricular myocytes to determine by Western blots and by 32P incorporation the optimal treatment time and the optimal dose for CaMK activation. In series I, cocaine, 10−6 mol/L, increased myocyte CaMKII translocation from myocyte soluble to particulate fractions by ≥73 ± 9% (P < 0.01) in comparison with controls but did not cause the translocation of CaMKI or CaMKIV. In series II and III, cocaine treatment of myocytes for 15 minutes increased maximal CaMKII activity by 86.5 ± 13.3% (P < 0.001) and a cocaine dose of 5×10−6 mol/L increased CaMKII activity by 169.5 ± 18.1% (P < 0.001). In series IV we measured by silver staining β-myosin heavy chain protein (β-MHC) expression in myocytes before and after cocaine and also CaMK inhibition with KN-62 (1-[N,O-bis-(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazine). In these experiments, cocaine, 5×10−6 mol/L, increased myocyte protein concentration by 29.2 ± 2.8%, and β-MHC by 93.2 ± 8.8% (P < 0.001). In series V and VI, cocaine effects on calcium currents (ICa) and intracellular Ca2+ ([Ca2+]i) were determined before and after CaMK inhibition with KN-62 in rat myocytes. Cocaine, 10−6 mol/L, enhanced ICa peak amplitude in a voltage-dependent manner (by 173.9 ± 14.9% at −20 mV and by 38.4 ± 6.9% at 0 mV P < 0.01). Cocaine, 10−6 to 10−5 mol/L, in series VI promoted Ca2+ transients from myocyte sarcoplasmic reticulum and increased [Ca2+]i to 607 ± 141 × 10−9 mol/L (P < 0.05). KN-62 decreased cocaine-induced myocyte protein expression by 76.6%, and β-MHC by 66.2% (P < 0.01) and significantly decreased cocaine-induced Ca2+ transients and [Ca2+]i. We conclude that CaMKII activation is an important mechanism whereby cocaine can cause myocyte hypertrophy.

Human umbilical cord blood mononuclear cell-conditioned media inhibits hypoxic-induced apoptosis in human coronary artery endothelial cells and cardiac myocytes by activation of the survival protein Akt.

We have previously demonstrated in acute myocardial infarctions that human umbilical cord blood mononuclear cells (HUCBCs), which contain hematopoietic, endothelial, and mesenchymal stem cells, reduce acute myocardial infarction size by ≥50% and preserve LV contractility. We hypothesize that the beneficial effects of HUCBCs are due to secretion of biologically active factors that activate in cardiac endothelial cells and myocytes the cell survival protein Akt. We determined by protein microarrays the growth factors and anti-inflammatory cytokines secreted by HUCBCs into culture media during 12 h of hypoxia (1% O2). We then determined by Western blots the effects of cell-free media from hypoxic-conditioned HUCBCs (HUCM) on activation of the cell survival protein Akt in human coronary artery endothelial cells and cardiac myocytes in culture during 24 h of 1% O2. We also determined in separate experiments endothelial cell and myocyte apoptosis by caspase-3 and Annexin V. In the present experiments, HUCBCs secreted multiple growth factors, anti-inflammatory cytokines, and inhibitors of metalloproteinase during normoxia and hypoxia. Human cord blood cells increased the concentration in culture media of angiopoietin, hepatocyte growth factor, interleukin-4, insulin-like growth factor, placental growth factor, vascular endothelial cell growth factor, angiogenin, and stem cell factor by 100 to >10,000% during 12 h of 1% O2 (p < 0.001). HUCM, which contained these biological factors, significantly increased Akt phosphorylation/activation in coronary artery endothelial cells and cardiac myocytes subjected to 24 h of 1% O2 by more than 60% (p < 0.05) and increased the antiapoptotic protein Bcl-2 expression by 34–50% in comparison with endothelial cells and myocytes treated without HUCM in 1% O2 (p < 0.05). HUCM also significantly decreased caspase-3 activity and decreased hypoxic endothelial cell and cardiac myocyte apoptosis by more than 40% in comparison with cells cultured without HUCM (p < 0.05). Inhibition of Akt activation in endothelial cells and myocytes by the sensitive and specific antagonist API-1 during 24 h of hypoxia nearly completely prevented the beneficial effects of HUCM on inhibiting caspase-3 activity and apoptosis. We conclude that HUCBCs secrete biologically active factors during hypoxia that activate survival proteins in endothelial cells and myocytes that significantly limit apoptosis.