Effects of dibutyryl cyclic 3',5'-adenosine monophosphate on the renal function

Accumulation of 125I in the oocytes, thyroids, and plasma of laying Japanese quail treated with cyclic AMP, theophylline, or prostaglandins E1 or E2

Dibutyryl cyclic AMP, theophyline, or prostaglandins E1 or E2 were injected intraperitoneally into laying Japanese quail in an attempt to stimulate increased transference of iodide by the ovarian membranes. Theophyline induced increased 18-hr 125I accumulations (by 7 to 18% of the injected dose) of borderline significance in the growing oocytes of some test groups. Theophyline plus DBcAMP treatment lead to a slight increase in 125I accumulation in the thyroid. Other treatments had no apparent effect on 125I transference. The prostaglandins induced oviposition within minutes of injection, as has been reported for uterine application of prostaglandins by other investigators. Means for plasma 125I levels for treated quail were 1.7 to 12.5 times greater than control levels. Values for oocyte to plasma and thyroid to plasma 125I ratios, it appeared that DBcAMP, theophyline, and the prostaglandins inhibited rather than stimulated the accumulation of 125I by the ovary and thyroid of the quail.

Effects of colchicine and vinblastine on the cellular action of vasopressin in mammalian kidney. A possible role of microtubules

To evaluate the possible role of microtubules in the cellular action of vasopressin on the mammalian kidney, the effects of microtubule-disrupting agents were studied in vivo and in vitro. In vivo studies were done in rats in mild to moderate water diuresis induced by drinking 5% glucose. Microtubule-disrupting alkaloids, colchicine (0.1 mg/day) or vinblastine (0.08 mg/day), given intraperitoneally, did not change water and solute excretion itself, but blocked or markedly inhibited the antidiuretic response (increase in urine osmolality and decrease in urine flow) to exogenous vasopressin. Total solute excretion was unaffected by these two alkaloids and there were no substantial changes in excretion of sodium, potassium, or creatinine. Lumicolchicine, a derivative of colchicine that does not interact with microtubules, did not alter the antidiuretic response to exogenous vasopressin. Activities of adenylate cyclase in the renal medullary plasma membrane, and cyclic AMP phosphodiesterase and protein kinase in renal medullary cytosol, were not influenced by 10(-5)-10(-4) M colchicine or vinblastine in vitro. Studies on the subcellular distribution of microtubular protein (assessed as [(3)H]colchicine-binding protein) in renal medulla shows that this protein is contained predominantly in the cytosol. Particulate fractions, including plasma membrane, contain only a minute amount (less than 6%) of the colchicine-binding activity. The results suggest that the integrity of cytoplasmic microtubules in cells of the distal nephron is required for the antidiuretic action of vasopressin, probably in the sites distal to cyclic AMP generation in the mammalian kidney.