Document Detail

Factors involved in the generation of tension during contraction to high potassium in the rat vas deferens.
MedLine Citation:
PMID:  2641885     Owner:  NLM     Status:  MEDLINE    
A large number of studies indicate that K(+)-induced contractions of smooth muscle depend on extracellular calcium. If these contractions depend exclusively on extracellular calcium then contractile responses to 140 mM K+, which are larger than the response to 35 mM K+, should be associated with a larger influx of 45Ca. This is not the case in the vas deferens from reserpine pretreated rats. During a 2 min interval, 45Ca influx induced by 140 mM K+ was identical to that produced by 35 mM K+. This suggests that a second mechanism may be involved in responses to high K+. Indeed, 140 mM K+ caused an approximately 300% increase above control in the formation of inositol trisphosphate (IP3) in tissues prelabelled with 3H-myoinositol whereas 35 mM K+ did not increase IP3. IP3 is thought to cause the release of calcium from internal stores which is consistent with our finding of an increase in 45Ca efflux into calcium-free medium from tissues prelabelled with 45Ca and stimulated with 140 mM K+. Stimulation with 35 mM K+ did not influence 45Ca efflux. We conclude that in the rat vas deferens high K+ promotes tension development by smooth muscle by a dual mechanism: influx of extracellular calcium and release of calcium from internal stores via an IP3 mechanism.
M A Khoyi; M A Smith; I L Buxton; D P Westfall
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Cellular signalling     Volume:  1     ISSN:  0898-6568     ISO Abbreviation:  Cell. Signal.     Publication Date:  1989  
Date Detail:
Created Date:  1990-10-18     Completed Date:  1990-10-18     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  8904683     Medline TA:  Cell Signal     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  599-605     Citation Subset:  IM    
Department of Pharmacology, University of Nevada, School of Medicine, Reno 89557.
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MeSH Terms
Calcium / metabolism
Inositol Phosphates / metabolism
Muscle Contraction / physiology*
Muscle, Smooth / metabolism*,  physiology
Potassium / physiology*
Rats, Inbred Strains
Vas Deferens / physiology
Grant Support
Reg. No./Substance:
0/Inositol Phosphates; 7440-09-7/Potassium; 7440-70-2/Calcium

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

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