Caveolin-1 and caveolin-3 regulate [Ca.sup.2+] homeostasis of single smooth muscle cells from rat cerebral resistance arteries

The role of caveolins, signature proteins of caveolae, in arterial [Ca.sup.2+] regulation is unknown. We investigated modulation of [Ca.sup.2+] homeostasis by caveolin-1 and caveolin-3 using smooth muscle cells from rat cerebral resistance arteries. Membrane current and [Ca.sup.2+] transients were simultaneously measured with voltage-clamped single cells. Membrane depolarization triggered [Ca.sup.2+] current and increased intracellular [Ca.sup.2+] concentration ([[Ca.sup.2+]].sub.i]). After repolarization, elevated [[Ca.sup.2+]].sub.i] returned to the resting level. [Ca.sup.2+] removal rate was determined from the declining phase of the [Ca.sup.2+] transient. Application of caveolin-1 antibody or caveolin-1 scaffolding domain peptide, corresponding to amino acid residues 82-101 of caveolin-1, significantly slowed [Ca.sup.2+] removal rate at a measured [[Ca.sup.2+]].sub.i] of 250 nM, with little effect at a measured [[Ca.sup.2+]].sub.i] of 600 nM. Application of caveolin-3 antibody or caveolin-3 scaffolding domain peptide, corresponding to amino acid residues 55-74 of caveolin-3, also significantly slowed [Ca.sup.2+] removal rate at a measured [[Ca.sup.2+]].sub.i] of 250 nM, with little effect at a measured [[[Ca.sup.2+]].sub.i] of 600 nM. Likewise, application of calmodulin inhibitory peptide, autocamtide-2-related inhibitory peptide, and cyclosporine A, inhibitors for calmodulin, [Ca.sup.2+]/calmodulin-dependent protein kinase II, and calcineurin, also significantly inhibited [Ca.sup.2+] removal rate at a measured [[Ca.sup.2+]].sub.i] of 250 nM but not at 600 nM. Application of cyclopiazonic acid, a sarcoplasmic reticulum [Ca.sup.2+] ATPase inhibitor, also significantly inhibited [Ca.sup.2+] removal rate at a measured [[Ca.sup.2+]].sub.i] of 250 nM but not at 600 nM. Our results suggest that caveolin-1 and caveolin-3 are important in [Ca.sup.2+] removal of resistance artery smooth muscle cells. caveolin-1 scaffolding domain peptide; caveolin-3 scaffolding domain peptide; calmodulin; calcium/calmodulin-dependent protein kinase II; calcineurin doi:10.1152/ajpheart.00669.2006