Atsushi Sugiyama1, Nu Nu Aye1, Yutaka Yatomi2,
Yukio Ozaki2 and Keitaro Hashimoto1
Departmentﾊof Pharmacology and 2Department of Laboratory Medicine,
Yamanashi Medical University
Tamaho-cho, Nakakoma-gun, Yamanashi 409-3898, Japan
Abstract: Recent studies have indicated that sphingosineﾊ1-phosphate
(Sph-1-P) is released into the blood flow from activated platelets upon
stimulation to exhibit a wide spectrum of biological functions. The purpose
of the present study was to assess the acute cardiovascular effects of circulating
Sph-1-P in the in vivo rat model. Intravenous administration of Sph-1-P
decreased the heart rate, ventricular contraction and blood pressure, while
it hardly affected the atrioventricular and intraventricular conduction.
Sph-1-P did not affect the adenylate cyclase activities of the membrane
preparations made from the right atrium and left ventricle. These results
suggest that functional receptors like lysophospholipid receptor Edg-1,
which can inhibit adenylate cyclase via Gi protein, are lacking
in the rat heart. Moreover, these observations will provide a clue to better
understand the various types of Sph-1-P—related pathophysiological
processes.
Keywords: Sphingosine 1-phosphate, Heart rate, Blood pressure, Contraction,
Adenylate cyclase