Referenced in: none

Automatically associated channels: Kir2.3

Title: Cell growth-dependent expression of endothelin-1 provocable Ca2+ channels in cloned vascular smooth muscle cells.

Authors: T Suzuki, T Toyo-oka, W S Shin, T Sugimoto

Journal, date & volume: J. Cardiovasc. Pharmacol., 1991 , 17 Suppl 7, S187-9

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/1725327

Abstract
To analyze the action of endothelin-1 (ET-1) on intracellular Ca ion ([Ca2+]i) handling, we have measured the [Ca2+]i transients in a cultured vascular smooth muscle cell (VSMC) line, A7r5, using two-dimensional microfluorophotometry. In the presence of 1 mM extracellular Ca2+ ([Ca2+]e), ET-1 (100 nM) induced a transient increase in [Ca2+]i due to Ca2+ release from sarcoplasmic reticulum and a subsequent sustained [Ca2+]i increase, suggestive of the entry via the voltage-dependent Ca2+ channel. The transient phase was heterogenous in the VSMC population; only two-thirds of VSMCs showed the phase, whereas all cells showed the sustained phase. To elucidate the cause of heterogeneity, we measured the [Ca2+]i using VSMCs cultured under two extreme conditions. When the cell cycle was arrested at the quiescent phase in the defined serum-free medium, the transient phase was observed in most cells. In contrast, when cell growth was promoted by the above medium plus PDGF (50 ng/ml), the [Ca2+]i response was completely abolished, whereas both the voltage-dependent Ca2+ channel and vasopressin-operated Ca2+ mobilization mechanism were universally preserved, irrespective of the culture conditions. These results may imply that the ET-1-mediated Ca2+ release mechanism is closely influenced by cell growth and preferentially effective at the quiescent phase.