A Na(+)-sensitive cation channel modulated by angiotensin II in cultured intestinal myocytes

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1994-06-01
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Nouailhetas, Viviane Louise Andree [UNIFESP]
Aboulafia, Jeannine [UNIFESP]
Frediani-Neto, E. [UNIFESP]
Ferreira, Alice Teixeira [UNIFESP]
Paiva, Antonio Cechelli de Mattos [UNIFESP]
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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 Ba2+ or Cs+ at the cellular side of the patch but was insensitive to Ca2+ or ATP. This channel had poor selectivity concerning cations (P-Li > 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 NPo 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 Ca2+ channels open.
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American Journal Of Physiology-cell Physiology. Bethesda: Amer Physiological Soc, v. 266, n. 6, p. C1538-C1543, 1994.
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