Ca V 1.2 N‐terminal splice variants regulate cerebral artery diameter

Voltage‐dependent Ca 2+ (Ca v 1.2) channels are the major Ca 2+ entry pathway in arterial myocytes and are essential for myogenic constriction. Alternative splicing of Ca V 1.2 α 1 subunit exon 1 generates two different N‐terminal variants in arterial myocytes (Ca V 1.2e1b and Ca V 1.2e1c). Here, we examined physiological functions of Ca v 1.2 α 1 subunit N‐terminal splice variants in cerebral artery myocytes. Acute application of a membrane‐permeant peptide corresponding to the Ca V 1.2e1c N‐terminus inhibited myocyte voltage‐dependent Ba 2+ currents and reversibly dilated pressurized arteries. Overexpression of the exon1‐encoded N‐terminus of Ca V 1.2e1b or Ca V 1.2e1c reduced pressure‐induced vasoconstriction (myogenic tone). shRNA targeting exon 1b selectively reduced Ca V 1.2e1b by ~39% and myogenic tone (at 60 mmHg) by ~34%. shRNA to exon 1c selectively reduced Ca V 1.2e1c by ~62% and myogenic tone by ~57%. shRNA targeting α 2 δ‐1, a Ca V 1.2 auxiliary subunit, reduced α 2 δ‐1 by ~57 % and plasma membrane‐localized (measured using biotinylation) Ca V 1.2e1b by ~54% and Ca V 1.2e1c by ~35%. Data indicate that both Ca V 1.2e1b and Ca V 1.2e1c modulate cerebral artery diameter and that α 2 δ‐1 differentially regulates plasma membrane trafficking of Ca V 1.2 N‐terminus variants. NIH HL67061, HL094378.