WATER-FLOW ACROSS THE PECTORAL AND VENTRAL PELVIC PATCH IN RANA-CATESBEIANA

Total and regional (pelvic and pectoral) osmotic water flow (J(v), cm3 . cm-2 . s-1 X 10(-7)) were measured in living and dead Rana catesbeiana. Dehydration caused the total-animal J(v) to increase from 14 +/- 1 (n = 6) to 73 +/- 14 (n = 7), while stopping the heart with an overdose of MS-222 caused a 56% drop in the dehydrated total-animal J(v) to 27 +/- 5 (n = 6). Regional J(v) at the pelvic site was significantly higher than pectoral or total-animal flows, with dehydration causing an increase from 265 +/- 92 to a maximum of 879 +/- 71 (n = 6). As in total-animal experiments, the high pelvic J(v) of dehydrated frogs could not be maintained when the heart was stopped and dropped to 356 +/- 48. These experiments show that an intact circulatory system is necessary to maintain the high osmotic water flow seen in a dehydrated frog and that regional flows are high enough to indicate that unstirred layers may be involved.