Regulation of pelvic patch water flow in Bufo marinus: role of bladder volume and ANG II.
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.
Parsons
R H
RH
Department of Biology, Rensselaer Polytechnic Institute, Troy, New York 12180-3590.
McDevitt
V
V
Aggerwal
V
V
Le Blang
T
T
Manley
K
K
Kim
N
N
Lopez
J
J
Kenedy
A A
AA
D000804:Angiotensin II / Q000494:pharmacology / Q000502:physiology*; D000818:Animals; D002024:Bufo marinus / Q000378:metabolism*; D003681:Dehydration / Q000378:metabolism; D004326:Drinking / Q000187:drug effects / Q000502:physiology; D007267:Injections; D010388:Pelvis; D012039:Regional Blood Flow; D012504:Saralasin / Q000494:pharmacology; D012867:Skin / Q000098:blood supply / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism; D001743:Urinary Bladder / Q000502:physiology*; D014867:Water / Q000378:metabolism*
D014867:Water; D000804:Angiotensin II; D012964:Sodium; D012504:Saralasin