Halothane-induced renal vasodilation.

Halothane-induced changes in renal function have generally been attributed to alterations in systemic hemodynamics, sympathetic tone, and various hormones. Studies were performed to determine whether halothane directly affects the kidney. Twenty-one canine kidneys were perfused in vitro utilizing hemodilution, pulsatile flow, and membrane oxygenation. Temperature and arterial blood-gas variables were controlled and mean and pulse pressures were maintained. Four experimental periods (I-IV)(each consisting of two 10-min sample collection periods) were conducted, with a 20-min "rest" period between succeeding experimental periods (elapsed time = 140 min). Responsiveness was assured by obtaining a normal response to furosemide, acetylcholine, or epinephrine after Period IV. In eight additional kidney preparations halothane was administered to achieve either a "low" (17 +/- 3 mg/100 ml) or "high" (35 +/- 5 mg/100 ml) concentration in Period II, the sequence reversed for Period III, and halothane eliminated by Period IV. Halothane produced marked increases in blood flow (21-26 per cent), total (203-267 per cent) and fractional (173-179 per cent) sodium excretion, osmolal clearance (62-111 per cent) and urinary volume (130-161 per cent). These changes were associated with a shift of microspheres from outer to inner cortex, and were completely reversible by eliminating the halothane. In the absence of external influences, halothane produces renal vasodilation and natriuresis. Direct tubular depression cannot be ruled out.

Observations on spermatogenesis and inseminative behavior of Megalodiscus temperatus adults in frogs.

Upon in vitro exposure to 3H-adenosine, spermatogonial cells in adult Megalodiscus temperatus were readily labeled on autoradiograms. At least 20 days were required for these cells to produce labeled sperm, the longest time reported so far for digenetic trematodes. Labelled worms transplanted to hosts for 24--31 days showed both self- and cross-insemination in multiple infections. When alone, half of the transplanted adults self-inseminated.

Autoregulation of renal blood flow during halothane anesthesia.

Renal blood flow, when not affected by humoral or neural influences, remains relatively constant over a wide range of renal arterial perfusion pressures. This phenomenon, referred to as "autoregulation," is an important mechanism allowing kidneys to maintain homeostasis of the internal milieu over a wide range of arterial pressures. The present study showed that 0.9 per cent halothane had no effect on autoregulation in an isolated, perfused dog kidney as renal arterial perfusion pressure was varied between 75 and 125 torr.