AJP - Regulatory, Integrative and Comparative Physiology, Vol 234, Issue 5 172-R177, Copyright © 1978 by American Physiological Society
Circulatory effects on osmotic water exchange in Rana pipiens
T. M. Mahany and R. H. Parsons
Tritiated water (3H2O) exchange was shown to be more sensitive to
circulatory changes than to arginine vasopressin (ADH)-induced permeability
changes. Reducing the circulation (sciatic artery ligation) and increasing
the circulation (severing the sciatic nerve) caused the 3H2O exchange in
frog legs to decrease from 6.0 +/- 1.3 (5) to 3.5 +/- 0.5 and increase from
6.0 +/- 0.7 (10) to 8.6 +/- 0.6 ml.h-1, respectively. In contrast injection
of ADH caused a negligible increase in 3H2O exchange from whole frogs,
while at the same time causing a significant increase in osmotic water
exchange from 0.22 +/- 0.08 (6) to 0.63 +/- 0.13 (6) g.100 cm-2.h-1.200
mosM-1. Circulatory changes in whole frogs were produced by inducing a
diving bradycardia that was less pronounced in a bath aerated with oxygen
than with air. The bradycardia caused a reduction in skin circulation, as
measured by 3H2O exchange, from 0.210 +/- 0.007 (16) to 0.17 +/- 0.006 (16)
ml.h-1.cm-2 in air mixed media and from 0.149 +/- 0.009 (16) to 0.135 +/-
0.011 (16) in oxygen mixed media. Diving bradycardia was also found to
affect osmotic water uptake which decreased from 0.61 +/- 0.05 (16) to 0.39
+/- 0.03 (16) g.100 cm-2.h-1.200 mosM-1 in air mixed media and from 0.61
+/- 0.05 (16) to 0.51 +/- 0.04 (16) in oxygen mixed media. The results
indicate that circulation affects osmotic water exchange.
