Calcium channel activity increased by plasma from ischemic hindlimbs of rats

Role of an endogenous no synthase inhibitor

Jong Shiaw Jin, Dixon W. Wilde, R Clinton Webb, Louis G. D'Alecy

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

We tested the hypothesis that an endogenous nitric oxide synthase (NOS) inhibitor released from ischemic hindlimbs increases the activity of calcium channels in vascular smooth muscle, thus contributing to the increased contractile response to calcium agonists. Hindlimb ischemia was generated in rats by infrarenal aortic cross clamping for 5 h, after which plasma was obtained from femoral vein blood. Incubating naive aortic rings (endothelium intact) for 2 h in plasma collected from ischemic rats significantly reduced relaxation to acetylcholine in precontracted rings and increased contraction to the calcium channel agonist, BAY K 8644. However, in isolated smooth muscle cells (without endothelium) loaded with fura-2, no difference was noted in BAY K 8644-stimulated intracellular calcium concentration. The contractile responses to sodium fluoride, serotonin, and calcium ionophore A23187 were not different in either ischemic or control plasma-incubated rings. The augmentation of the contractile response to BAY K 8644 was significantly inhibited by nitroglycerin (10 -8 M) and by exposure to calcium-free solution. N(ω)-nitro-L-arginine (without plasma incubation)- pretreated rings also demonstrated hyperresponsiveness to BAY K 8644. The increase in responsiveness to BAY K 8644 exhibited a negative correlation with the maximal relaxation to acetylcholine (r = -0.99), suggesting that the apparent increase in activity of calcium channels is mediated through inhibition of nitric oxide by an endogenous NOS inhibitor on endothelium.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume270
Issue number4 39-4
StatePublished - May 13 1996
Externally publishedYes

Fingerprint

Calcium Channels
Hindlimb
Endothelium
Calcium
Nitric Oxide Synthase
Acetylcholine
Calcium Channel Agonists
Sodium Fluoride
Femoral Vein
Calcium Ionophores
Fura-2
Calcimycin
Nitroglycerin
Vascular Smooth Muscle
Constriction
Smooth Muscle Myocytes
Arginine
Serotonin
Nitric Oxide
Ischemia

Keywords

  • aortic surgery
  • fura-2
  • hypertension
  • intermittent claudication
  • protein kinase C
  • vascular smooth muscle

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

Cite this

Calcium channel activity increased by plasma from ischemic hindlimbs of rats : Role of an endogenous no synthase inhibitor. / Jin, Jong Shiaw; Wilde, Dixon W.; Webb, R Clinton; D'Alecy, Louis G.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 270, No. 4 39-4, 13.05.1996.

Research output: Contribution to journalArticle

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