Document Detail

Systemic hypertension induces disparate localized left ventricular action potential lengthening and altered sensitivity to verapamil in left ventricular myocardium.
MedLine Citation:
PMID:  3959090     Owner:  NLM     Status:  MEDLINE    
Previously, we demonstrated that acute exposure to superfusate containing verapamil suppresses action potential plateau to a greater degree in cells at the tip of the anterior papillary muscle compared to those at its base in normal cat left ventricle (LV) studied in tissue bath. To determine the effects of chronic pressure overload brought about by renal hypertension on papillary muscle electrophysiology and regional sensitivity to verapamil, LV were isolated from cats subjected to unilateral nephrectomy and contralateral kidney wrapping. After 3 months, systemic hypertension (mean increase = 60.2 +/- 1.4 mmHg) was associated with moderate LV hypertrophy of approximately equal to 18% (LV weight/body weight). Transmembrane action potentials recorded from the endocardial surface (including anterior papillary muscle) in pressure overloaded LV in vitro (800 ms stimulus cycle length) showed increased action potential duration at 25, 75 and 90% of repolarization (APD25, APD75 and APD90, respectively) relative to controls (LV from normal and sham operated cats). With respect to the anterior papillary muscle in pressure overloaded LV, APD25, APD75 and APD90 were increased to a greater extent in cells at the base of the muscle compared to those increases observed at the tip (P less than 0.05). In contrast to its effects in controls, verapamil (2 micrograms/ml) significantly reduced APD25 at both the base and the tip of the papillary muscle in pressure overloaded preparations, but particularly at the base; also, the disparities between the APD75 or APD90 at tip and base were decreased. Thus, regional electrophysiologic disparities were induced in systemic hypertension, and these differences were subsequently reduced by verapamil.(ABSTRACT TRUNCATED AT 250 WORDS)
J S Cameron; L S Miller; S Kimura; C J Kaiser; D R Campbell; P L Kozlovskis; M S Gaide; R J Myerburg; A L Bassett
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:  Journal of molecular and cellular cardiology     Volume:  18     ISSN:  0022-2828     ISO Abbreviation:  J. Mol. Cell. Cardiol.     Publication Date:  1986 Feb 
Date Detail:
Created Date:  1986-05-05     Completed Date:  1986-05-05     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0262322     Medline TA:  J Mol Cell Cardiol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  169-75     Citation Subset:  IM    
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MeSH Terms
Action Potentials / drug effects*
Cardiomyopathies / physiopathology
Electric Stimulation
Heart Conduction System / physiopathology
Heart Ventricles / drug effects,  physiopathology*
Hypertension, Renal / physiopathology*
Papillary Muscles / drug effects,  physiopathology
Verapamil / pharmacology*
Grant Support
Reg. No./Substance:

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