Differing 45Ca efflux responses in cultured canine aortic smooth muscle cells and canine aortic media-intimal strips
Kutsky, P.; Weiss, G.B.
Archives Internationales de Pharmacodynamie et de Therapie 246(1): 47-60
1980
ISSN/ISBN: 0003-9780 PMID: 7447550 Document Number: 161612
Vascular smooth muscle tissue culture preparations were developed to examine 45Ca efflux in a more homogeneous cellular system than isolted arterial strips. The effect of altering the extracellular Ca2+ concentration or addition of La3+ on 45Ca efflux was compared in cultured canine aortic vascular smooth muscle cells and intact canine aortic media-intimal strips. Enzymatically dispersed cells from the canine aortic medial layer were grown in flasks and primary cultures were utilized in 5-14 days. Measurement of 45Ca efflux was attained by incubating attached cells in 45Ca and subsequently washing this out with added serial nonradioactive aliquots which were collected. When the Ca2+ content of the washout solution was elevated 10-fold, the 45Ca efflux rate was decreased. When the washout solution Ca2+ level was decreased (from 1.8 to 0.1 mM) the 45Ca efflux rate was increased. Addition of La3+ decreased the rate of 45Ca efflux. The effects of Ca2+ and La3+ suggest that a portion of the 45Ca efflux from cultured smooth muscle cells may be dependent upon a transport or exchange process that is inhibited by extracellular Ca2+. In canine aortic media-intimal strips, raising the Ca2+ concentration (from 1.8 to 18 mM) increased 45Ca efflux, and lowering the Ca2+ concentration (from 1.8 to 0.1 mM) decreased 45Ca efflux; addition of La3+ to the washout solution had no significant effect on 45Ca efflux. The observed effects of altering Ca2+ concentration and adding La3+ on 45Ca efflux differ qualitatively in isolated aortic media-intimal strips and cultured aortic smooth muscle cells.