Mechanosensitive nonselective cation channel facilitation by endothelin-1 is regulated by protein kinase C in arterial myocytes.

OBJECTIVE: The mechanosensitive nonselective cation channel (NSC(MS)) and endothelin-1 (ET-1) play critical roles in the regulation of vascular tone. This study was undertaken to investigate the effect of ET-1 on NSC(MS) and on the myogenic response of arteries.

METHODS: Cell-attached patch-clamp techniques were applied to rabbit pulmonary and cerebral arterial smooth muscle cells using a 140 mM CsCl pipette and bath solutions (Ca(2+)-free, 1 mM EGTA). Myogenic responses were determined by video analysis of pressurized arteries.

RESULTS: The application of negative pressures through the pipette activated NSC(MS), and this was augmented by bath application of ET-1 (1 pM-30 nM). ET-1 lowered the lowest pressure required for NSC(MS) activation. NSC(MS) facilitation by ET-1 was prevented by BQ-123 (1 microM, an ET(A) antagonist) but not by BQ-788 (1 microM, an ET(B) antagonist). Phorbol 12-myristate 13-acetate (PMA, 100 nM), a protein kinase C activator, also increased the activity of NSC(MS). ET-1- or PMA-induced facilitation of NSC(MS) was abolished by GF109203X (10 microM), a protein kinase C inhibitor. Video analysis of pressurized cerebral artery showed inhibition of the myogenic response by the NSC(MS) channel blockers GsMTx-4 (5 microM) and DIDS (3-100 microM). Treatment with ET-1 (10 pM) augmented the myogenic response and this was inhibited by DIDS (30 microM).

CONCLUSION: Stimulation of ET-1 receptor (ET(A)) facilitates NSC(MS) via a protein kinase C-dependent signaling pathway in rabbit arterial myocytes. Our findings suggest that NSC(MS) play a role in the myogenic response and its augmentation by ET-1.