Effect of propranolol and nifedipine on in vitro fluid absorption by the isolated perfused proximal convoluted tubule of the rabbit.
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".
Figueiredo
J F
JF
Departamento de Clínica Médica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Brasil.
Falkenstein
D
D
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
D011433:Propranolol; D009543:Nifedipine