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Marked dissociation between intracellular Ca2+ level and contraction on exposure of rat aorta to lysophosphatidylcholine.

Abstract：

:We investigated the relationship between tension development and the cytosolic free Ca2+ level ([Ca2+]i) on exposure of the endothelium-denuded isolated rat aorta to palmitoyl-L-alpha-lysophosphatidylcholine. Lysophosphatidylcholine concentration-dependently induced a gradual increase in [Ca2+]i. Application of 10(-4) M lysophosphatidylcholine induced a large and sustained tonic increase in [Ca2+]i (the peak [Ca2+]i was 125.2 +/- 11.5% of the 80 mM K+-induced response) but only a small contraction (4.0 +/- 1.4% of the 80 mM K+ induced contraction). The sustained increase in [Ca2+]i was attenuated when extracellular Ca2+ was removed but it was unaffected by verapamil or 1-(5-isoquinolinesulphonyl)-2-methylpiperazine dihydrochloride (H-7). Digitonin also produced a gradual increase in [Ca2+]i but with a pronounced contraction. Triton X-100 (0.1%) produced a marked elevation in [Ca2+]i with no detectable contraction. Triton X-100, however, caused a rapid leakage of fura PE-3. Treatment with 10(-4) M lysophosphatidylcholine for 1 or 2 h did not affect the contractile response induced by 80 mM K+ and this treatment did not release lactate dehydrogenase from the rat aorta. Treatment with lysophosphatidylcholine did not affect either the cyclic AMP level or the cyclic GMP level in endothelium-denuded aortic tissues. These results show that in the rat aorta lysophosphatidylcholine produces a large increase in [Ca2+]i (possibly in a non-contractile compartment) which does not induce contraction. Thus, the increase in [Ca2+]i induced by lysophosphatidylcholine (i) requires external Ca2+ but is not due to an increased Ca2+ influx through voltage-dependent L-type Ca2+ channels, (ii) is not primarily due to protein kinase C activation and (iii) is probably not due to a detergent action (like those of digitonin and triton X-100). The relative lack of a contractile response to lysophosphatidylcholine is not due to formation of cyclic AMP or cyclic GMP.

journal_name

Eur J Pharmacol

journal_title

European journal of pharmacology

authors

Suenaga H,Kamata K

doi

10.1016/s0014-2999(99)00458-6

keywords:

subject

Has Abstract

pub_date

1999-08-06 00:00:00

pages

177-86

issue

eissn

0014-2999

issn

1879-0712

pii

S0014-2999(99)00458-6

journal_volume

378

pub_type

杂志文章

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Marked dissociation between intracellular Ca2+ level and contraction on exposure of rat aorta to lysophosphatidylcholine.