Functional coupling of BKCa and P2X channels in human vascular smooth muscle cells

AGUSTÍN ASUAJE; MILESI VERONICA; ENRIQUE NICOLAS; MARTIN PEDRO; MONCADA, MELISA

Río de Janeiro

Congreso; 38th WORDL CONGRESS OF THE INTERNATIONAL UNION OF PHYSIOLOGAL SCIENCES; 2017

INTERNATIONAL UNION OF PHYSIOLOGAL SCIENCES

The application of extracellular ATP (ATPe) on isolated human vascular smooth muscle cells (SMC) evoked, in physiological conditions, a transient inward current mainly carried by Na+ and Ca2+, characterized by a fast activation and a peak current followed by a decrease toward the baseline value, which represents the desensitization of ATP receptors. As it is not totally define the role of this Ca2+ influx on the SMC physiology, we worked on its possible functional coupling with the large conductance voltage and Ca2+ activated K+ channels (BKCa). This potassium channel has a very important modulation role of SMC contractile state, since it has a high sensitivity for Ca2+, and so the same signal that would produce contraction on SMC (increased intracellular Ca2+) could also stop the contraction or even generate relaxation, due to hyperpolarization of cells membrane potential. Whole-cell patch clamp experiments showed a significant increase in BKCa macroscopic current immediately after application of 100 uM ATPe and coincidentally we observed also a significant movement of the reverse potential to more negative values (n=6, p