A Na (+) -sensitive cation channel modulated by angiotensin II in cultured intestinal myocytes
Nouailhetas, V.L.; Aboulafia, J.; Frediani-Neto, E.; Ferreira, A.T.; Paiva, A.C.
American Journal of Physiology 266(6 Pt 1): C1538-C1543
1994
ISSN/ISBN: 0002-9513 PMID: 7517631 Document Number: 427989
Single-channel currents were recorded in excised inside-out and cell-attached patches of cultured cells from the longitudinal smooth muscle of the guinea pig ileum. In the presence of symmetrical high-K+ solutions, we identified a voltage-dependent 12-pS channel. It was reversibly blocked by addition of either Ba-2+ or Cs+ at the cellular side of the patch but was insensitive to Ca-2+ or ATP. This channel had poor selectivity concerning cations (P-Li gt P-K = P-Na = P-Ca, where P is permeability) and low permeability to anions. Isosmotic substitution of NaCl for KCl in the solution facing the cellular side enhanced the channel activity by increasing NP-o values where N is number of channels and P-o is open probability. In the cell-attached configuration, the channel was also activated by addition of angiotensin II in the bath solution. We propose that this nonselective cation channel might play a role in the control of the membrane potential during the contractile response of the guinea pig ileum to agonists by keeping the voltage-sensitive Ca-2+ channels open.