Flow-Dependent Modulation of Endothelial Ca²⁺ Dynamics by Small Conductance Ca²⁺-Activated K⁺ Channels in Mouse...

Small conductance Ca²⁺ activated K⁺ channels (K_Ca2.3) are important regulators of vascular function. They provide Ca²⁺-dependent hyperpolarization of the endothelial membrane potential, promoting agonist-induced vasodilation. Another important mechanism of influence may occur through positive feedback regulation of endothelial Ca²⁺ signals, likely via amplification of influx through membrane cation channels. K_Ca2.3 channels have recently been implicated in flow-mediated dilation of the arterial vasculature and may contribute to the crucial homeostatic role of shear stress in preventing vascular wall remodeling and progressive vascular disease (i.e., atherosclerosis). The impact of K_Ca2.3 channels on endothelial Ca²⁺ signaling under physiologically relevant shear stress conditions remains unknown.

In the current study, we employ mice expressing an endothelium-specific Ca²⁺ fluorophore (cdh5-GCaMP8) to characterize the K_Ca2.3 channel influence on the dynamic Ca²⁺ signaling profile along the arterial endothelium in the presence and absence of shear-stress.

Our data indicate K_Ca2.3 channels have a minimal influence on basal Ca²⁺ signaling in the carotid artery endothelium in the absence of flow, but they contribute substantially to amplification of Ca²⁺ dynamics in the presence of flow and their influence can be augmented through exogenous positive modulation.

The findings suggest a pivotal role for K_Ca2.3 channels in adjusting the profile of homeostatic dynamic Ca²⁺ signals along the arterial intima under flow.