title: 8-BrcAMP-induced capacitance and transport of H2O and Na in skin and urinary bladder of urodele amphibians.
abstract: The effects of 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) on capacitance (C), osmotic water flow (Jv), and amiloride-sensitive short-circuit current (INa) were studied in bladder and skin derived from the tiger salamander (aquatic and postmetamorphosed terrestrial phase). 8-BrcAMP-dependent increases in C, measured from the transepithelial voltage response to constant current pulses, occurred in aquatic (delta C = 44%) and terrestrial (delta C = 61%) bladders and terrestrial skin (delta C = 19%). Jv (200-mosM gradient, mucosal side hypotonic) was observed in the bladders and was further enhanced by addition of 8-BrcAMP [10(-3) M; delta Jv = 0.42 microliter.min-1.microF-1 (aquatic) and 0.32 microliter.min-1.microF-1 (terrestrial)]. The aquatic and terrestrial skins were relatively impermeable to water, but the terrestrial skin showed a small response to 8-BrcAMP (delta Jv = 0.04 microliter.min-1.microF-1). 8-BrcAMP-mediated natriferic responses were observed in aquatic bladder (delta INa = 62%) and terrestrial skin (delta INa = 105%). Antidiuretic hormone (ADH)-induced Jv was also observed in the aquatic bladder (delta Jv = 0.33 microliter.min-1.microF-1) and was similar to the 8-BrcAMP-mediated Jv measured in this tissue. The terrestrial bladder displayed a more vigorous response to 8-BrcAMP than to ADH (delta JvADH = 0.09 microliter.min-1.microF-1 and delta Jv8-BrcAMP = 0.32 microliter.min-1.microF-1), suggesting that diminished sensitivity to ADH accompanies the transition from water to land in this species.
authors.affiliation: Department of Physiology, Cornell University Medical College, New York, New York 10021.
authors.forename: R B
authors.initials: RB
authors.lastname: Silver
authors.forename: L G
authors.initials: LG
authors.lastname: Palmer
mesh_terms: D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology*; D000064:Acclimatization; D000557:Ambystoma; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D001834:Body Water / Q000378:metabolism*; D004553:Electric Conductivity; D066298:In Vitro Techniques; D007700:Kinetics; D009092:Mucous Membrane / Q000187:drug effects / Q000502:physiology; D012867:Skin / Q000187:drug effects; D012879:Skin Physiological Phenomena; D012964:Sodium / Q000378:metabolism*; D001743:Urinary Bladder / Q000187:drug effects / Q000502:physiology*
chemical_list: D015124:8-Bromo Cyclic Adenosine Monophosphate; D000584:Amiloride; D012964:Sodium