Multiple types of ryanodine receptor/Ca2+ release channels are expressed in vascular smooth muscle.

Functional studies on vascular smooth muscle suggest the presence of ryanodine receptors (RyRs) with differing properties. In an attempt to understand such differences we investigated, using reverse transcription-polymerase chain reaction (RT-PCR), the possibility that smooth muscle cells express multiple types of RyRs. RNA was extracted from rat aorta, superior and small mesenteric arterial vessels, purified aortic smooth muscle media, or cultured aortic smooth muscle cells for cDNA synthesis. The cDNAs encoding RyR1, RyR2, and RyR3 were amplified using PCR primers based on sequences close to the 3' coding region of the RyR genes and PCR products verified by restriction endonuclease analysis. All three members of the RyR gene family were found to be present in vascular smooth muscle. This finding of multiple types of RyRs expressed in the same cell type indicates a complex mechanism of RyR Ca2+ channel regulation involving the formation of homo- and/or heterotetrameric complexes.