Role of cytosolic ca2+ and protein kinase c in developing myogenic
contraction in isolated rat small arteries.
Karibe, Akihiko, Jun Watanabe, Satoru Horiguchi, Masaharu Takeuchi,
Shu Suzuki, Masayuki Funakoshi, Hiroshi Katoh, Mitsumasa Keitoku,
Shoichi Satoh, and Kunio Shirato.
First Department of Internal Medicine, Tohoku University School of
Medicine
APStracts 3:0458H, 1996.
Cytosolic Ca2+ and protein kinase C (PKC) may regulate the myogenic
contraction of arterial myocytes. The role of these second messengers
are examined in skeletal muscle small arteries (ASK) which have
strong myogenic activity and mesenteric small arteries (AMS) which
have weak myogenic activity. The vessels were isolated and
cannulated. The inner diameter was measured with a video-digitizing
system. [Ca2+]i was assessed by fura-2. ASK dilated from 122(6 to
153(6 (m immediately after the transmural pressure change from 40 to
100 mmHg and constricted to 121(5 (m (myogenic contraction) with an
increase in the 340/380 fluorescent ratio (by 33%) in control state.
Nifedipine[umlaut]u@abolished myogenic contraction and the
fluorescent ratio increase.[umlaut]u@PKC inhibitors (H7 and
staurosporine) abolished myogenic contraction, but did not depress
the fluorescent ratio increase. In AMS, myogenic contraction was
insignificant in control.[umlaut]u@A relatively low dose of PKC
activator (4.4(1.4 nmol/L) elicited myogenic contraction, but a
higher dose (21(6 nmol/L) rather depressed. Thus, the cytosolic Ca2+
increase and PKC activity may cooperatively act on the myogenic
contraction of ASK. The activity of PKC should play an important role
in myogenic contraction of rat small arteries.
Received 26 January 1996; accepted in final form 11 September
1996.
APS Manuscript Number H80-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996