Renal and hemodynamic effects of diltiazem after elective major vascular surgery--a potential renoprotective agent?

A postoperative study was done of the effects of an infusion of diltiazem (DTZ), 1 microgram.kg-1.min-1 after a bolus dose of 0.28 mg.kg-1 on renal function and hemodynamics in 10 patients who were operated with insertion of an abdominal aortic graft. Urine flow, glomerular filtration rate (GFR) by inulin clearance, and renal plasma flow (RPF) by PAH clearance and fractional excretion of electrolytes and osmols were measured for three periods of 20 min during infusion of DTZ, in the morning after surgery. Systemic hemodynamic studies were conducted and serum levels of catecholamines were measured. GFR increased during the initial period of DTZ infusion. There were no significant changes during the study period in any of the other parameters, compared to baseline, except for a decrease in heart rate from 84 to 77 beats per minute. The absence of a sustained increase in GFR and a natriuretic and diuretic effect may possibly be ascribed to a preexisting nonconstricted status of the renal vasculature. The authors conclude that the dose of DTZ used in this study can be safely used for further investigations to elucidate the effects of peroperative infusion of DTZ on renal function in connection with major vascular surgery.

Saponin-induced release of cell-surface-anchored Thy-1 by serum glycosylphosphatidylinositol-specific phospholipase D.

A glycosylphosphatidylinositol-specific phospholipase D (GPI-PLD) was purified from human serum and used for studies on the release of GPI-anchored Thy-1 glycoprotein from mouse T lymphoma cells Y191. Previous studies have shown that whereas GPI-PLD is highly active against detergent-solubilized GPI-anchored proteins, it is normally unable to release GPI-containing proteins anchored in a lipid bilayer. Confirming these findings, the addition of GPI-PLD to intact Y191 cells did not result in cleavage of Thy-1. However, pretreatment of cells with saponin, a cholesterol-sequestering agent, rendered Thy-1 susceptible to hydrolysis. Very little solubilization of GPI-containing Thy-1 occurred under these conditions. From experiments with reconstituted liposomes it was inferred that the effect of saponin on cells was to aid in the presentation of Thy-1 to GPI-PLD. Furthermore, it was concluded that cholesterol-saponin complexes formed in the membrane were not alone responsible for the effect. Rather, additional molecules in the plasma membrane are possibly involved in the presentation of Thy-1 on saponin-treated cells. This finding may have implications for a physiological role of circulating GPI-PLD in the regulation of GPI-anchored proteins on cells.

[Experimental study on the effect of 11-deoxyprostaglandin E1 on hormonal balance in animals]. / Eksperimental'noe issledovanie vliianiia 11-dezoksiprostaglandina El na gormonal'nyi balans zhivotnykh.

The effects of prostaglandin F2 alpha and (+/-) 11-deoxyprostaglandin E1 (DPGE) on the levels of progesterone and estradiol in the blood plasma or serum of experimental animals were studied and compared. It was found for the first time that the synthetic analog of natural PGE1, DPGE, is capable to substantially reduce the progesterone level in the blood (rats and cows) and to induce the luteolysis of yellow bodies in the cow ovaries. It was demonstrated that DPGE promotes the resolution of both cyclic and persistent yellow bodies. The pattern of the drug action on rat blood steroid hormones depends on the time of pregnancy and is most pronounced in the last trimester of pregnancy.