Effects of ADH on single nephron glomerular filtration rates in the avian kidney

Effects of ADH (arginine vasotocins on the total kidney glomercular filtration rate (GFR) and on single nephron glomerular filtration rates (SNGFR) of reptilian type (RT) and mammalian type (MT) nephrons were studied in desert quail, Lophortyx gambelii. Low, probably physiological, doses (10 and 50 ng/kg) of arginine vasotocin (AVT) had no effect on mean arterial blood pressure, but caused reduction in total kidney GFR primarily as a result of the decrease in the number of filtering RT nephrons. High, probably pharmacological, doses (200 ng/kg) of AVT produced increases, decreases, or biphasic changes in mean arterial blood pressure. With decreases or biphasic changes in mean arterial blood pressure, total kidney GFR, SNGFR of MT nephrons, and the number of filtering RT nephrons decreased. With increases in mean arterial pressure, total kidney GFR decreased, SNGFR or MT nephrons increased, and RT nephrons ceased filtering. The possible changes in intrarenal blood flow responsible for these effects on SNGFR, the possible relationship of effects of AVT and salt load on SNGFR, and the possible relationship of changes in the number of filtering RT nephrons to concentrating ability are discussed.