Mladen Boban

Red wine induced modulation of vascular function: separating the role of polyphenols, ethanol, and urates

By using red wine (RW), dealcoholized red wine (DARW), polyphenols-stripped red wine (PSRW), ethanol-water solution (ET), and water (W), the role of wine polyphenols, ethanol, and urate on vascular function was examined in humans (n=9 per beverage) and on isolated rat aortic rings (n=9). Healthy males randomly consumed each beverage in a cross-over design. Plasma ethanol, catechin, and urate concentrations were measured before and 30, 60 and 120 minutes after beverage intake. Endothelial function was assessed before and 60 minutes after beverage consumption by normalized flow-mediated dilation (FMD). RW and DARW induced similar vasodilatation in the isolated vessels whereas PSRW, ET, and W did not. All ethanol-containing beverages induced similar basal vasodilatation of brachial artery. Only intake of RW resulted in enhancement of endothelial response, despite similar plasma catechin concentration after DARW. The borderline effect of RW on FMD (P=0.0531) became significant after FMD normalization (P=0.0043) that neutralized blunting effect of ethanol-induced basal vasodilatation. Effects of PSRW and ET did not differ although plasma urate increased after PSRW and not after ET, indicating lack of urate influence on endothelial response. Acute vascular effects of RW, mediated by polyphenols, cannot be predicted by plasma catechin concentration only.

Direct comparative effects of isoflurane and desflurane in isolated guinea pig hearts

The aim of this study was to test if myocardial and coronary vascular effects of desflurane and isoflurane were similar in the isolated heart. The cardiac effects of these anesthetics were examined in 12 guinea pig hearts perfused in a retrograde manner. Spontaneous heart rate, atrioventricular (AV) conduction time, systolic left ventricular pressure and coronary flow were measured. To differentiate direct vasodilatory effects of these anesthetics from an indirect metabolic effect due to autoregulation of coronary flow, O2 delivery (DO2), myocardial O2 consumption (MVO2) and percent O2 extraction were also monitored. Isoflurane and desflurane were injected directly into sealed bottles containing oxygenated perfusate solution. Each heart was perfused randomly with these anesthetics. Anesthetic concentrations in the perfusate were 0.28 +/- 0.02 and 0.52 +/- 0.02 mM for isoflurane and 0.59 +/- 0.01 and 1.02 +/- 0.09 mM for desflurane (mean +/- standard error of the mean). Calculated vapor concentrations were 1.3 and 2.5 vol % for isoflurane and 6.8 and 11.8 vol % for desflurane which correspond to approximately 1 and 2 MAC in vivo. Each anesthetic similarly decreased heart rate and prolonged AV conduction time in a concentration-dependent manner. Left ventricular pressure (control 93 +/- 4 mmHg) decreased by 11 +/- 1% and 24 +/- 2% with isoflurane and by 15 +/- 1% and 30 +/- 2% with desflurane. The decreases in heart rate and pressure were accompanied by decreases in MVO2 of 12 +/- 2% and 30 +/- 3% with isoflurane and of 19 +/- 3% and 40 +/- 4% with desflurane from a control of 57 +/- 2 microliters.g-1.min-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Lack of Stereospecific Effects of Isoflurane and Desflurane Isomers in Isolated Guinea Pig Hearts

BackgroundVolatile anesthetics alter membrane channel proteins. It is controversial whether they act by nonspecifically perturbing lipid membranes or by directly binding to amphiphilic and usually stereoselective regions on channel macromolecules. Biologically relevant receptors are usually stereoselective. The stereochemical effect of Isoflurane and desflurane can be used as a pharmacologic tool to investigate whether these drugs bind to specific target sites. The specific optical isomers of isoflurane and desflurane were used to examine whether they produce any differential effects on electrical, mechanical, and metabolic function in isolated hearts. MethodsIsolated guinea-pig hearts were perfused with Krebs-Ringers solution containing, in random order, both isomers of either isoflurane (n = 11) or desflurane (n = 6) for 10 min with a 15-min washout period. Either anesthetic was injected into a preoxygenated, sealed bottle of perfusate, which gave concentrations of 0.28 and 0.57 min for isoflurane and 0.48 and 0.88 mM for desflurane, which are equivalent to 1 and 2 MAC multiples. ResultsBoth isomers of isoflurane and desflurane decreased left ventricular pressure, heart rate, and percent oxygen extraction and increased atrloventricular conduction time, coronary flow, and oxygen delivery. Each change was significantly different from control at each concentration, and these effects were greater with the high compared to the low concentration of each anesthetic. There was no significant difference between the (+)- and the (-)-isomers for either anesthetic for any measured or calculated variable. Also, the effects of the stereoisomers were similar to those of the racemic mixture. ConclusionThese data indicate that the optical isomers of Isoflurane and desflurane are equipotent, as assessed by their effects on cardiac function in isolated guinea-pig hearts. Although both agents may ultimately influence hydrophilic domains of the protein channels, their major cardiac effect appears to result either from global perturbation of the membrane lipids and/or an interaction at nonstereoselective sites on channels modulating cardiac anesthetic effects.

Contraction uncoupling with butanedione monoxime versus low calcium or high potassium solutions on flow and contractile function of isolated hearts after prolonged hypothermic perfusion.

BACKGROUND Normal ionic perfusate containing butanedione monoxime (BDM), a reversible myofilament inhibitor, could be better than either a high potassium (KCl) or a low calcium (CaCl2) perfusate for long-term cardiac preservation. This hypothesis was tested in 70 isolated guinea pig hearts. METHODS AND RESULTS Three groups--time control (8 hours, 37 degrees C), cold control (22 hours, 3.8 degrees C), and cold+BDM (22 hours)--were perfused with typical Krebs-Ringer solution (2.5 mmol/L CaCl2 and 4.5 mmol/L KCl). Two other groups were cold perfused for 22 hours either with 2.5 mmol/L CaCl2 + 20 mmol/L KCl (high) or with 0.5 mmol/L CaCl2 (low) + 4.5 mmol/L KCl. These changes were maintained from 20 minutes before cold perfusion until 30 minutes after rewarming to 37 degrees C. Coronary vasodilator reserve was tested before cold perfusion and 2 hours after warm reperfusion with adenosine (Ade), acetylcholine (Ach, endothelium dependent), and nitroprusside (NP, endothelium independent). Each treatment decreased left ventricular pressure (LVP) by more than 80% before cold perfusion. During warm reperfusion, LVP was lower in cold control (-72 +/- 5%), high KCl (-76 +/- 4%), and low CaCl2 (-80 +/- 4%) groups than in BDM (-38 +/- 3%) or time control (-18 +/- 4%) groups; coronary flow (CF) was lower in high KCl (-67 +/- 4%) and low CaCl2 (-54 +/- 7%) groups than in cold control (-37 +/- 6%), BDM (-30 +/- 5%), or time control (+2 +/- 3%) groups; and percent oxygen extraction (controls, 62 +/- 4%) was higher in the high KCl group (83 +/- 6%) than in cold control (72 +/- 3%), BDM (73 +/- 3%), low CaCl2 (72 +/- 5%), or time control (63 +/- 3%) groups. CF responses to Ade, Ach, and NP (+103 +/- 7%, +24 +/- 5%, and +34 +/- 5% before cold) were attenuated (+76 +/- 6%, +18 +/- 5%, and +23 +/- 4%) in the time control group (5 hours later), were reduced but present in the BDM group (+10 +/- 5%, -5 +/- 5%, and -5 +/- 5%), and were absent in both low CaCl2 and high KCl groups after 2 hours of reperfusion. CONCLUSIONS Normal ionic BDM solution better preserves cardiac function and basal CF after prolonged cold perfusion than do cold control, high KCl, and low CaCl2 solutions. Vasodilatory capacity is markedly diminished after perfusion with either the high KCl or the low CaCl2 solution.

Antioxidant and vasodilatory effects of blackberry and grape wines.

In contrast to the well-described various biological effects of grape wines, the potential effects of commonly consumed blackberry wine have not been studied. We examined in vitro antioxidant and vasodilatory effects of four blackberry wines and compared them with the effects of two red and two white grape wines. Although some blackberry wines had lower total phenolic content relative to the red grape wines, their antioxidant capacity was stronger, which may be related to a higher content of non-flavonoid compounds (most notably gallic acid) in blackberry wines. Although maximal vasodilation induced by blackberry wines was generally similar to that of red wines, blackberry wines were less potent vasodilators. Vasodilatory activity of all wines, in addition to their flavonoid and total phenolic content, was most significantly associated with their content of anthocyanins. No association of vasodilation with any individual polyphenolic compound was found. Our results indicate the biological potential of blackberry wines, which deserves deeper scientific attention.

Differences in Vasodilatory Response to Red Wine in Rat and Guinea Pig Aorta

We examined and compared mechanisms of the red wine (RW)-induced vasorelaxation in guinea pig (GP) and rat aorta. Acetylcholine-induced relaxation of norepinephrine-precontracted aortic rings was stronger in rat aorta than in GP aorta, whereas RW-induced vasorelaxation was stronger in GP aorta. l-nitro-arginine methyl ester (l-NAME) abolished RW-induced vasorelaxation in rat aorta, whereas in GP aorta, it was only reduced by 50%. To examine mechanisms of the l-NAME-resistant relaxation, GP aortic rings were additionally exposed to indomethacin, clotrimazole, and their combination. Indomethacin insignificantly reduced RW-induced relaxation, but in combination with l-NAME, the relaxation was synergistically decreased (80%). After clotrimazole exposure, the relaxation was reduced by 25%, and addition of indomethacin caused no further reduction. Only the combination of l-NAME, indomethacin, and clotrimazole prevented RW-induced vasorelaxation. RW-induced vasorelaxation in KCl-precontracted GP rings was significantly smaller (Emax 78.31% ± 6.09%) than the RW-induced relaxation in norepinephrine-precontracted rings (Emax 126.01% ± 2.11%). l-NAME in KCl-precontracted GP rings prevented RW-induced vasorelaxation. In conclusion, different pathways are involved in the RW-induced vasorelaxation in GP aorta, in contrast to rat aorta, in which NO plays main role. Therefore, the uncritical extrapolation of the results from one species to another could be misleading.

Effects of l-Arginine and Nω-Nitro-l-Arginine Methyl Ester on Cardiac Perfusion and Function After 1-Day Cold Preservation of Isolated Hearts

BACKGROUND Coronary flow responses to endothelium-dependent (acetylcholine [ACh] or 5-hydroxytryptamine [5-HT]) and endothelium-independent (adenosine [ADE] or nitroprusside [NP]) vasodilators may be altered before and after 1-day hypothermia during the perfusion of arginine vasopressin (AVP), D-arginine (D-ARG), L-arginine (L-ARG), or nitro-L-arginine methyl ester (L-NAME). METHODS AND RESULTS Four groups of guinea pig hearts (37.5 degrees C [warm]) were perfused for 6 hours with AVP, L-ARG, L-NAME, or nothing (control). Five heart groups (cold) were perfused with AVP, D-ARG, L-ARG, L-NAME, or nothing (control), but after 2 hours they were perfused at low flow for 22 hours at 3.7 degrees C and again for 3 hours at 37.5 degrees C. ADE, butanedione monoxime, and NP were given for cardioprotection before, during, and after hypothermia. In warm groups, L-ARG did not alter basal flow or ADE, ACh, 5-HT, or NP responses, whereas L-NAME and AVP reduced basal flow and the ADE response, abolished ACh and 5-HT responses, and increased the NP response. In cold groups after hypothermia. L-ARG did not alter basal flow, but L-NAME, AVP, D-ARG, and control reduced flow. In the postcold L-ARG group, ACh increased peak flow, but NP did not increase flow in other cold groups. Effluent L-ARG and L-CIT in the cold control group fell from 64 +/- 9 and 9 +/- 1 micrograms/L at 1 hour to 36 +/- 5 and 5 +/- 1 micrograms/L at 25 hours, respectively. Left ventricular pressure and cardiac efficiency improved more in the postcold L-ARG group than in the postcold D-ARG, AVP, and L-NAME groups. CONCLUSIONS Endogenous effluent levels of L-ARG and L-CIT decrease after 24 hours in isolated hearts, whereas perfusion of L-ARG improves cardiac performance, basal coronary flow, and vasodilator responses. In contrast, L-NAME, L-ARG, and AVP limit flow and performance but maintain a partial vasodilatory response to NP. Sustained release of NO may account for improved performance after L-ARG after hypothermia.

A complex pattern of agreement between oscillometric and tonometric measurement of arterial stiffness in a population-based sample

Objective: Arterial stiffness can be estimated by several noninvasive methods. In a large population-based sample we performed an agreement analysis of the set of arterial stiffness indices (ASIs) measured by tonometric (SphygmoCor) and oscillometric (Arteriograph) techniques. Methods: Central augmentation index (cAIx) and peripheral augmentation index (pAIx), as well as central SBP (cSBP) were measured in 1012 participants from a population-based study. Data were analyzed using Bland–Altman agreement analysis, multivariate adaptive regression splines and Fishers linear discriminant analysis. Results: In contrast to high initial correlation between two devices (r = 0.87 for pAIx, 0.88 for cAIx and 0.95 for cSBP), plotting against each other the values of measured ASIs revealed their uneven distribution and grouping into three distinctive clusters of participants. The strongest cluster discriminators were age and DBP (cluster 1: age <40, DBP 70.42 ± 7.41; cluster 2: age >40, DBP 77.36 ± 10.16; cluster 3: age >60, DBP 82.56 ± 9.48). Bland–Altman analysis of clusters showed complex differences in agreement pattern for cAIx and pAIx. For cAIx SphygmoCor gives lower readings, especially in cluster 1, whereas for pAIx Arteriograph gives lower readings in cluster 1 and higher readings in clusters 2 and 3. The agreement for pAIx was better in younger participants and the same for cAIx in older participants. Conclusion: ASIs obtained by SphygmoCor and Arteriograph cannot be interchangeably used as they seem to be differently influenced by predictors of arterial stiffness, predominantly by age. Different pattern of pAIx and cAIx agreement across clusters demonstrates importance of distinguishing cAIx and pAIx. Homogeneity of the study population for age should be considered when interpreting results of the studies investigating ASI.

Coronary Flow Response to Vasodilators in Isolated Hearts Cold Perfused for One Day with Butanedione Monoxime

Objectives Impaired tissue reperfusion may be an important limiting factor for long-term hypothermic cardiac preservation. Cardiac function and recovery of coronary responses to endothelium independent and dependent vasodilators were tested before and after one day of preservation by cold perfusion with a normal extracellular solution containing the contraction uncoupler 2,3, butanedione monoxime (BDM) with or without reperfusion with nitroprusside (NP) plus adenosine (Ade) or plus the nucleoside transport inhibitor, nitrobenzylthioinosine (NBTI).Methods Guinea pig hearts (n = 70) were isolated and perfused at constant pressure during normothermic conditions (37°C). Groups 1 and 2 were perfused for 8 hrs without cold perfusion (time control); group 2 was also infused with arginine vasopressin (AVP) for 6 hrs; groups 3–5 were infused with BDM before, during, and initially after 22 hrs of constant, low flow hypothermic (3.8°C) perfusion; group 3 was also infused with NP and Ade, and group 4 with NP and NBTI...

Normative equations for central augmentation index: assessment of inter-population applicability and how it could be improved

Common reference values of arterial stiffness indices could be effective screening tool in detecting vascular phenotypes at risk. However, populations of the same ethnicity may differ in vascular phenotype due to different environmental pressure. We examined applicability of normative equations for central augmentation index (cAIx) derived from Danish population with low cardiovascular risk on the corresponding Croatian population from the Mediterranean area. Disagreement between measured and predicted cAIx was assessed by Bland-Altman analysis. Both, cAIx-age distribution and normative equation fitted on Croatian data were highly comparable to Danish low-risk sample. Contrarily, Bland-Altman analysis of cAIx disagreement revealed a curvilinear deviation from the line of full agreement indicating that the equations were not equally applicable across age ranges. Stratification of individual data into age decades eliminated curvilinearity in all but the 30–39 (men) and 40–49 (women) decades. In other decades, linear disagreement independent of age persisted indicating that cAIx determinants other than age were not envisaged/compensated for by proposed equations. Therefore, established normative equations are equally applicable to both Nordic and Mediterranean populations but are of limited use. If designed for narrower age ranges, the equations’ sensitivity in detecting vascular phenotypes at risk and applicability to different populations could be improved.