Methods for the Isolation of and Study of Ca2+ Signaling in Arteriolar Smooth Muscle Cells

Arterioles in the microcirculation significantly contribute to peripheral vascular resistance, regulate the distribution of blood flow within a tissue, and participate in the regulation of capillary pressure and, hence, fluid balance. Methods for the bulk isolation of arteriolar smooth muscle cells (SMCs) by enzyme perfusion of tissues such as brain, kidney, and heart have been reported. Isolated cremasteric arteriolar SMCs also have been used to study global Ca²⁺ signals induced by norepinephrine, and the role-played by voltage-gated Ca²⁺ channels (VGCCs) in this process. Enzymatically-isolated cremaster arteriolar SMCs do not display ryanodine-receptor-mediated Ca²⁺ sparks that have been reported in SMCs isolated from, for example, cerebral arteries and intact piglet cerebral resistance arteries and arterioles. The authors use enzymatically isolated arteriolar SMCs to explore the cell-specific expression of mRNA for ion channels involved in arteriolar Ca²⁺ signaling. Isolated arteriolar SMCs can also be used to examine protein expression using immunolocalization approaches. Agonist-induced contraction can also be studied using enzymatically isolated arteriolar SMCs.