AJP - Regulatory, Integrative and Comparative Physiology, Vol 264, Issue 6 1260-R1265, Copyright © 1993 by American Physiological Society
Regulation of pelvic patch water flow in Bufo marinus: role of bladder volume and ANG II
R. H. Parsons, V. McDevitt, V. Aggerwal, T. Le Blang, K. Manley, N. Kim, J. Lopez and A. A. Kenedy
Department of Biology, Rensselaer Polytechnic Institute, Troy, New York 12180-3590.
This report examines the importance of bladder volume in regulating
cutaneous water uptake (Jv, cm3.cm-2.s-1 x 10(-7)) across the ventral
pelvic patch and examines the role of angiotensin II (ANG II) and
circulation as the regulatory mechanism. Jv in empty-bladder Bufo marinus
(bladder volume 3.89 +/- 1.49%, n = 7) was 1,671 +/- 68 (n = 7). Injection
of Ringer solution into the bladder (12.8 +/- 2.2%, n = 7) decreased Jv to
1,025 +/- 202 (n = 7). ANG II injected into toads with filled bladders
increased Jv in a dose-dependent manner. At 5 micrograms/100 g toad Jv
increased by 136 +/- 63 (n = 6), at 50 micrograms/100 g toad by 432 +/- 82
(n = 7), and at 200 micrograms/100 g toad by 620 +/- 142 (n = 5). Saralasin
(200 micrograms/100 g toad) completely inhibited the response to ANG II (50
micrograms/100 g toad) and at 1 mg/100 g toad decreased Jv in empty-bladder
toads. These experiments indicate that 1) bladder volume participates in
the regulation of Jv in the ventral pelvic patch; 2) ANG II increases the
Jv in toads with full bladders; 3) saralasin inhibits the high Jv in empty
bladder toads; 4) the high Jv, associated with an empty bladder, requires
an intact circulation to be maintained; 5) without an intact circulation,
the high water flow associated with an empty bladder causes the Na+ content
of the tissue in the ventral patch to be reduced; and 6) ANG II causes only
a minimal increases in water permeability in the isolated pelvic patch
skin.
