Soon Pyo Hong

Comparison of green tea extract and epigallocatechin gallate on blood pressure and contractile responses of vascular smooth muscle of Rats

The present study was conducted to investigate the effects of green tea extract (GTE) on arte-rial blood pressure and contractile responses of isolated aortic strips of the normotensive rats and to establish the mechanism of action. The phenylephrine (10~p6~10~p5M)-induced contrac-tile responses were greatly inhibited in the presence of GTE (0.3–1.2 mg/mL) in a dose-depen-dent fashion. Also, high potassium (3.5x10-p2~5.6x1CTp2 M)-induced contractile responses were depressed in the presence of 0.6–1.2 mg/mL of GTE, but not affected in low concentration of GTE (0.3 mg/mL). However, epigallocatechin gallate (EGCG, 4–12 ug/mL) did not affect the contractile responses evoked by phenylephrine and high Kp+. GTE (5–20 mg/kg) given into a femoral vein of the normotensive rat produced a dose-dependent depressor response, which is transient. Interestingly, the infusion of a moderate dose of GTE (10 mg/kg/30 min) made a significant reduction in pressor responses induced by intravenous norepinephrine. However, EGCG (1 mg/kg/30 min) did not affect them. Collectively, these results obtained from the present study demonstrate that intravenous GTE causes a dose-dependent depressor action in the anesthetized rat at least partly through the blockade of adrenergic α1-receptors. GTE also causes the relaxation in the isolated aortic strips of the rat via the blockade of adrenergic α1-receptors, in addition to the unknown direct mechanism. It seems that there is a big differ-ence in the vascular effect between GTE and EGCG.

Non-invasive recognition of generalized coronary arteriosystemic fistulae by contrast echocardiography and multidetector CT

Coronary artery fistulae, including generalized coronary arteriosystemic fistulae, are usually identified incidentally during invasive coronary angiographies. Generalized or multiple coronary arteriosystemic fistulae arise from all three major coronary arteries draining into the left ventricular chamber. In a patient with generalized coronary arteriosystemic fistulae, myocardial ischemia and diastolic volume overload of the left ventricle can be caused by a left-to-left shunt; however, the clinical and hemodynamic consequences are incompletely understood. We report the case of generalized coronary arteriosystemic fistulae in a 73-year-old female who presented with mild exertional dyspnea as an anginal equivalent. This case report represents the complementary, non-invasive role of transthoracic contrast echocardiography and multidetector computed tomography (MDCT) coronary angiography in the early recognition of generalized coronary arteriosystemic fistulae by demonstrating a plexus of multiple small vessels emptying exclusively into the left ventricle.

Influence of pentobarbital-Na on stimulation-evoked catecholamine secretion in the perfused rat adrenal gland.

Objectives The present study was attempted to investigate the effects of pentobarbital-Na, one of the barbiturates which are known to depress excitatory synaptic transmission in the central nervous system at concentrations similar to those required for the induction and maintenance of anesthesia, on catecholamines (CA) secretion evoked by cholinergic stimulation and membrane-depolarization from the isolated perfused rat adrenal gland, and to clarify the mechanism of its action. Methods Mature male Sprague-Dawley rats were anesthetized with thiopenal-Na(40mg/kg, s.c.). The adrenal gland was isolated by the methods of Wakade. A cannula used for perfusion of the adrenal gland was inserted into the distal end of the renal vein. The adrenal gland was carefully removed from the animal and placed on a platform of a leucite chamber. Results The perfusion of pentobarbital-Na(30–300uM) into an adrenal vein for 20 min produced relatively dose-dependent inhibition in CA secretion evoked by ACh(5.32mM) DMPP(100uM for 1 min), McN-A-343(200uM for 2 min), Bay-K-8644(10uM) and high potassium(56mM), while it did not affect the CA secretion of cyclopiazonic acid(10uM). Also, in the presence of thiopental-Na (100uM), CA secretory responses evoked by ACh, DMPP, McN-A-343 and high K+ were markedly depressed. Moreover, in adrenal glands preloaded with ketamine(100uM for 20 min), which is known to be a dissociative anesthetic, CA secretion evoked by ACh, DMPP, McN-A-343 and high K+ were significantly attenuated. Conclusion Taken together, these experimental results suggest that pentobarbital-Na depresses CA release evoked by both cholinergic stimulation and membrane-depolarization from the isolated rat adrenal medulla and that this inhibitory activity may be due to the result of the direct inhibiton of Ca++ influx into the chromaffin cells without any effect on the calcium mobilization from the intracellular store.

Influence of Amineptine on Changes of Blood Pressure Evoked by Norepinephrine and Dopamine

The influence of amineptine, an antidepressant currently employed having mainly selective dopaminergic neurochemical activity, on the pressor responses evoked by norepinephrine (NE) and dopamine (DA) was studied in anesthetized whole rats. Amineptine at doses of 0.5, 1.5, and 5.0 mg/kg/30 min infused into the femoral vein of the rat caused a dose-related inhibition of the pressor responses of NE and DA. The hypertensive responses of NE and DA augmented by pretreatment with reserpine, a catecholamine depletor, were also clearly depressed following the infusion of amineptine with a rate of 1.5 mg/kg/30 min. Furthermore, the pressor responses of NE and DA potentiated by pretreatment with debrisoquin, a sympathetic neuron blocker, were markedly diminished after pretreatment with the infusion of amineptine at the above same rate (1.5 mg/kg/30 min). These experimental results demonstrate that amineptine causes an inhibitory effect on the pressor responses evoked by NE and DA. It is thought that the amineptine effect may be due to the blockade of the peripheral adrenergic alpha-receptors in addition to the previously described uptake inhibition of dopamine.

Subepidermal capillary basement membrane thickness of the skin obtained by punch biopsy in patients with non insulin dependent diabetes mellitus.

Thickening and proliferation of the capillary basement membrane is a generalized phenomenon in diabetes mellitus and has been described in many organs including the heart, kidney, pancreas, retina etc. While such changes are specific, it is difficult to obtain specimens from those organs. Tissue samples were obtained from the medial surface of the thigh of 33 diabetics and 4 healthy controls by means of punch biopsy. Measurements carried out by normogram obtained from electron microscopic pictures. HbA1c values were also determined at time of muscle biopsy. The HbA1c values are higher in diabetics than in the control group (p<0.01). The subepidermal capillary basement membrane thickness of the diabetics: 30% of the 5’th decade population, 53.9% of the 6’th decade population and 83.3% of the 7’th decade population was greater than 3,000 A°. Whereas that of the controls was less than 3,000 A°. The subepidermal capillary basement membrane thickness was not significantly increased with the duration of the disease. In cases of greater subepidermal capillary besement membrane thickness, HbA1c showed a significant increase. (p<0.01).