title: Effect of propranolol and nifedipine on in vitro fluid absorption by the isolated perfused proximal convoluted tubule of the rabbit.
abstract: The inhibition of fluid absorption (Jv) by the antiarrhythmic and antihypertensive drugs propranolol and nifedipine, which increase cytosolic Ca2+ concentration, was studied using the isolated rabbit proximal convoluted tubule perfused in vitro. Proximal convoluted tubules were perfused and bathed with a modified Krebs-Henseleit solution containing bovine serum albumin. Jv was measured after a 30-min control period, after 40 min with either 0.1 mM propranolol or 1.0 mM nifedipine on the peritubular side and after a 40-min recovery period. Both drugs inhibited Jv (58% propranolol, and 21% nifedipine). The 40-min recovery period was sufficient to reverse the effect of nifedipine, but propranolol-treated tubules (N = 6) only reached 78% of the control Jv value. These results demonstrate that antiarrhythmic and antihypertensive drugs are powerful inhibitors of net fluid absorption by exerting a direct effect on proximal or distal tubule cells, thus acting like "local diuretics".
authors.affiliation: Departamento de Clínica Médica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Brasil.
authors.forename: J F
authors.initials: JF
authors.lastname: Figueiredo
authors.forename: D
authors.initials: D
authors.lastname: Falkenstein
mesh_terms: D000042:Absorption / Q000187:drug effects; D000818:Animals; D066298:In Vitro Techniques; D007687:Kidney Tubules, Proximal / Q000187:drug effects* / Q000378:metabolism; D009543:Nifedipine / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology*; D011817:Rabbits; D013997:Time Factors
chemical_list: D011433:Propranolol; D009543:Nifedipine