Pressure Regulation of Vascular L-type Calcium Channels

Abstract

Myogenic tone is dependent upon the activation of L-type Ca2+ channels and the rise in cytosolic [Ca2+]i. While L-type Ca2+ channel activation is often singularly linked to arterial depolarization, sparse evidence suggests that pressure itself may also enhance functional activity, through cooperative gating and trafficking. In this context, this study explored whether intravascular pressure indeed tune the myogenic response by enhancing the L-type Ca2+ channel trafficking and amplifying cooperative gating.Experimentation began in isolated smooth muscle cells (whole cell/single-channel patch clamp; immunohistochemistry; proximity ligation assay) and extended to intact arteries (pressure myography and Ca2+ measurements). Whole-cell electrophysiology revealed the ability of pressure stimuli to increase the L-type Ca2+ current, a response dependent on the intact cytoskeleton and enzymes tied to functional coupling (PKCα, AKAP150, PKA). Cell-attached electrophysiology confirmed whole-cell observations, registering increased coupling among L-type Ca2+ channels when cells were pressurized. Ensuing experiments on isolated arteries subsequently revealed linkage between intravascular pressure and enhanced L-type Ca2+ channel activity, independent of membrane depolarization.In closing, our results suggest there is more to L-type Ca2+ channel regulation than voltage gating and that pressure itself can enhance functional activity. Work continues to precisely define the pressure-sensitive signaling complexes within vascular smooth muscle. Supported by the Canadian Institute for Health Research, National Institute of Health and the Rorabeck Chair in Vascular Biology and Neuroscience. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.