Effect of bumetanide on potassium transport and ionic composition of the arterial wall

HORACIO CANTIELLO, JULIO COPELLO, ANGELICA MULLER, LIDIA MIKULIC, AND MARIO F. VILLAMIL

AMERICAN JOURNAL OF PHYSIOLOGY-CELL PHYSIOLOGY

Año: 1986 p. 537 - 546

0363-6143

Bumetanide (B) (I mM) decreased K content of dog carotid arteries (K,) by 11-E%, K turnover (X,) by 31%, and steady-state K fluxes (Jk) by -48%. The drug also reduced intracellular (ic) Cl, HzO, and occasionally ic Na. The halfmaximal inhibitory concentration of B on Jk was close to 40 PM. However, 10 PM still fully reduced ic K, Cl, and Hz0 but not ic Na. Replacement of external Cl by sulfate or nitrate mimicked the B effects on JK and reduced its capacity of inhibition by -40 and -8O%, respectively. Replacement of Na by choline decreased K, and Jk by 90 and 96%, respectively, and rendered B totally ineffective. B also decreased Cl uptake and content of cultured vascular smooth muscle and ic Cl and Hz0 of whole arteries. Ouabain (Ou) (1 mM) decreasedK , 90%, accelerated AZ four- to fivefold, and reduced Jk 45%. Addition of B or removal of external Na or Cl in the presence of Ou returned & to normal levels and reduced the residual Jk by -90% but failed to further decrease the K,. .According to these data, B mainly inhibits a coupled KC1 passive self exchange plus a smaller active net KC1 influx. Ou abolished the active component without affecting the passive self exchange. The presenceo f Na is necessaryfo r the operation of the KU-coupled self exchange, and Na gradients may provide the energy for the uphill KC1 movements. 11-E%, K turnover (X,) by 31%, and steady-state K fluxes (Jk) by -48%. The drug also reduced intracellular (ic) Cl, HzO, and occasionally ic Na. The halfmaximal inhibitory concentration of B on Jk was close to 40 PM. However, 10 PM still fully reduced ic K, Cl, and Hz0 but not ic Na. Replacement of external Cl by sulfate or nitrate mimicked the B effects on JK and reduced its capacity of inhibition by -40 and -8O%, respectively. Replacement of Na by choline decreased K, and Jk by 90 and 96%, respectively, and rendered B totally ineffective. B also decreased Cl uptake and content of cultured vascular smooth muscle and ic Cl and Hz0 of whole arteries. Ouabain (Ou) (1 mM) decreasedK , 90%, accelerated AZ four- to fivefold, and reduced Jk 45%. Addition of B or removal of external Na or Cl in the presence of Ou returned & to normal levels and reduced the residual Jk by -90% but failed to further decrease the K,. .According to these data, B mainly inhibits a coupled KC1 passive self exchange plus a smaller active net KC1 influx. Ou abolished the active component without affecting the passive self exchange. The presenceo f Na is necessaryfo r the operation of the KU-coupled self exchange, and Na gradients may provide the energy for the uphill KC1 movements.