Document Detail

Late gestational changes in sympathomimetic sensitivity in primagravid rabbit ligaments.
MedLine Citation:
PMID:  10926158     Owner:  NLM     Status:  MEDLINE    
The adrenoceptor profile of blood vessels supplying the medial collateral ligament (MCL) of virgin and primagravid (day 29 of pregnancy) rabbit knees was examined. Topical bolus administration of the alpha1-adrenoceptor agonists methoxamine and phenylephrine, and the alpha2-adrenoceptor agonist clonidine, to exposed knee joints resulted in a dose-dependent vasoconstriction of ligamentous vessels. The rank order of potency for the alpha-agonists was found to be phenylephrine > methoxamine > clonidine. Dobutamine, which acts on beta1-adrenoceptors, and ritodrine, which is a beta2-agonist, imparted a mild vasodilatatory effect on MCL blood vessels with the efficacy of ritodrine being greater than that of dobutamine. In primagravid rabbits, the constrictor effects of methoxamine and phenylephrine were significantly attenuated compared with virgin control animals (P < 0.0001), whereas clonidine-mediated vasoconstriction was unaltered in the gravid animal (P = 0.3957). With respect to beta-adrenoceptor activity, the dilatational effect of dobutamine was the same as in controls (P = 0.5294), while ritodrine vasoactivity was completely abolished in primagravid knees (P < 0.005). These findings suggest that the adrenergic control of rabbit MCL blood flow is predominantly mediated by postjunctional alpha1 and beta2-adrenoceptors. Pregnancy leads to either downregulation and (or) desensitisation of alpha1 and beta2-adrenoceptors in the ligament which could disrupt normal joint homeostasis.
J J McDougall; R C Bray; D A Hart
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Canadian journal of physiology and pharmacology     Volume:  78     ISSN:  0008-4212     ISO Abbreviation:  Can. J. Physiol. Pharmacol.     Publication Date:  2000 Jul 
Date Detail:
Created Date:  2000-11-28     Completed Date:  2000-11-28     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0372712     Medline TA:  Can J Physiol Pharmacol     Country:  CANADA    
Other Details:
Languages:  eng     Pagination:  528-34     Citation Subset:  IM    
McCaig Centre for Joint Injury and Arthritis Research, University of Calgary, AB, Canada.
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MeSH Terms
Dobutamine / pharmacology
Dose-Response Relationship, Drug
Medial Collateral Ligament, Knee / blood supply,  drug effects*
Methoxamine / pharmacology
Phenylephrine / pharmacology
Pregnancy, Animal / physiology*
Regional Blood Flow / drug effects
Sympathomimetics / pharmacology*
Reg. No./Substance:
0/Sympathomimetics; 34368-04-2/Dobutamine; 390-28-3/Methoxamine; 59-42-7/Phenylephrine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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