It is demonstrated that 17-[3-estradiol sulfate increases the electrical homogeneity of the myocardium as a result of reducing the differences in the duration of cardiomyocyte action potentials. Key Words: myocardium; transmembrane .potentials; estradiolOn the basis of autoradiography data it has been hypothesized that the heart is a target organ for both estrogens and androgens [7,8]. Although the cytosolic reception of estrogens predominates, it has been assumed that the membrane processes play an important role in the mechanism of action of steroid hormones [4,51.The heart of animals with transformed hormonal status (males treated with estrogens) is more resistant to arrhythmogenic factors and is more capable of spontaneous defibrillation [1,2,6]. Since it is difficult to distinguish between direct and indirect effects of estrogens on cardiomyocytes in vivo, the present study was carried out on isolated myocardial stripes. MATERIALS AND METHODSEighteen experiments were performed on isolated myocardial stripes excised from the left ventricle of guinea pig heart. The stripes were perfused with warm (33~ pH 7.3) oxygenated (95% 0,/5% CO2) Ringer solution containing (in mM): K(~I 4, NaC1 137, CaC1, 2, NaHPO 4 1.8, MgC12 2.7, NaHCO 3 1.75 g/liter, and glucose 2 g/liter. An aqueous solution of 17-[3-estradiol sulfate (10 -6 g/liter, 17-[3-ES, Sigma) was employed as an estrogen. The solution was changed every 3 min.The electrical activity of endocardial and epicardial cells was continuously recorded with a Tektronix 5103N oscilloscope, photocamera, and glass electrodes filled with 3 M KC1. The resting potential (RP), and the amplitude and duration of the action potential (AP) at 20, 50, and 80% repolarization were measured by the standard methods; the first derivative of the front of AP growth was determined.Statistical analysis was performed using PSI-PLOT software. RESULTSIn order to suppress sources of automaticity, the stripes were stimulated with a frequency of 1.4-2 Hz for 25-30 min. Under a light microscope, a microelectrode was inserted in cells of the trabecular muscles located on the endocardial surface. It was found

The direct venous pressure profile was recorded before and after treatment in 15 patients suffering from chronic venous insufficiency. Patients were treated conservatively, first by tight elastic support and walking exercises, then by eliminating the points of blood shunting by sclerotherapy of the incompetent perforators. The average venous pressure drop during tiptoeing was increased from 31.6% to 50.9% (P less tan 0.01), and the time required for return to the resting venous pressure level increased from an average 6 seconds to 12.9 seconds (P = 0.01). These values indicate a significant improvement in the functioning of the muscle pump of the calf, and are paralleled by clinical and subjective improvement. Wr recommend this method of treatment in cases of chronic venous insufficiency. We also wish to point out the importance of repeated direct venous pressure profile recording as a means of assessing the effectiveness of treatment in cases of venous disorders.

Changes in the transmembrane potentials of guinea pig cardiomyocytes caused by epinephrine and 17~-estradiol sulfate are studied. It is shown that 17~-estradiol attenuates the effect of epinephrine on these cells.