title: Genetic evidence for functional role of ryanodine receptor 1 in pulmonary artery smooth muscle cells.
abstract: Ryanodine receptor 1 (RyR1) is well-known to be expressed in systemic and pulmonary vascular smooth muscle cells (SMCs); however, its functional roles remain largely unknown. In the present study, we attempted to determine the potential importance of RyR1 in membrane depolarization-, neurotransmitter-, and hypoxia-induced Ca2+ release and contraction in pulmonary artery SMCs (PASMCs) using RyR1 homozygous and heterozygous gene deletion (RyR1-/- and RyR1+/-) mice. Our results indicate that spontaneous local Ca2+ release and caffeine-induced global Ca2+ release are significantly reduced in embryonic RyR1-/- and adult RyR+/- cells. An increase in [Ca2+]i following membrane depolarization with high K+ is markedly attenuated in RyR1-/- and RyR1+/- PASMCs in normal Ca2+ or Ca2+-free extracellular solution. Similarly, muscle contraction evoked by membrane depolarization is reduced in RyR1+/- pulmonary arteries in the presence or absence of extracellular Ca2+. Neurotransmitter receptor agonists and inositol 1,4,5-triphosphate elicit a much smaller increase in [Ca2+]i in both RyR1-/- and RyR1+/- cells. We have also found that neurotransmitter-evoked muscle contraction is significantly inhibited in RyR1+/- pulmonary arteries. Hypoxia-induced increase in [Ca2+]i and contraction are largely blocked in RyR1-/- and/or RyR1+/- PASMCs. Collectively, our findings provide genetic evidence for the functional importance of RyR1 in spontaneous local Ca2+ release, and membrane depolarization-, neurotransmitter-, as well as hypoxia-induced global Ca2+ release and attendant contraction in PASMCs.
authors.affiliation: Center for Cardiovascular Sciences (MC-8), Albany Medical College, 47 New Scotland Avenue, Albany, NY 12208, USA.
authors.forename: Xiao-Qiang
authors.initials: XQ
authors.lastname: Li
authors.forename: Yun-Min
authors.initials: YM
authors.lastname: Zheng
authors.forename: Rakesh
authors.initials: R
authors.lastname: Rathore
authors.forename: Jianjie
authors.initials: J
authors.lastname: Ma
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takeshima
authors.forename: Yong-Xiao
authors.initials: YX
authors.lastname: Wang
mesh_terms: D000818:Animals; D002110:Caffeine / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000502:physiology*; D005260:Female; D000860:Hypoxia / Q000378:metabolism; D008564:Membrane Potentials / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D009119:Muscle Contraction / Q000502:physiology; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000502:physiology*; D018377:Neurotransmitter Agents / Q000378:metabolism; D018408:Patch-Clamp Techniques; D011247:Pregnancy; D011651:Pulmonary Artery / Q000166:cytology*; D019837:Ryanodine Receptor Calcium Release Channel / Q000235:genetics / Q000378:metabolism
chemical_list: D018377:Neurotransmitter Agents; D019837:Ryanodine Receptor Calcium Release Channel; D002110:Caffeine; D002118:Calcium