[Heterogeneities in intracellular Ca2+ pools among different arterial smooth muscle cells and its possible role in vascular reactivities in rat].

J Cao, M Chen, Q Wang

The differences in intracellular Ca2+ pool capacities, the mutual relations between different agonist-sensitive Ca2+ pools (ASCaP) and between ASCaP and caffeine-sensitive Ca2+ pool (CSCaP), and the possible role of Ca2+ pool capacity in vascular reactivities in different isolated artery rings of rat in Ca(2+)-free media were studied by using the tension of vascular smooth muscle as an indicator of Ca2+ release. The study showed the following findings: (1) the Ca2+ pools were significantly different in capacities in different arteries (renal artery > mesenteric artery > caudal artery > aorta > pulmonary artery); (2) different ASCaPs were partially "overlapped", i.e., when one ASCaP was depleted, other kind of agonist could still induce a small but significant Ca2+ release; (3) the CSCaP was present in all the arteries tested, but it was not the same pool with the ASCaP; (4) there were no high-K+ depolarization-induced Ca2+ release in all the arteries tested and (5) there was a positive correlation between the maximal contraction (Emax expressed as mg force/mg muscle wet weight) and the Ca2+ pool capacities, suggesting that there is a role of Ca2+ pool capacities in the vascular contractilities.