Document Detail

Effects of bucumolol, nadolol and nifenalol on maximum upstroke velocity of action potential in guinea pig papillary muscles.
MedLine Citation:
PMID:  2872598     Owner:  NLM     Status:  MEDLINE    
The effects of bucumolol (BUC), nadolol (NAD) and nifenalol (NIF) on contractile forces and on action potentials (APs) were investigated in isolated guinea pig atrial and papillary muscles, respectively. Log 1/ED40 values for the negative inotropic effects of these drugs were 0.097, 10 and 0.74 mmol/l in this order. BUC (50 mumol/l), NAD (0.5 mmol/l) and NIF (0.2 mmol/l) produced about 60, 20 and 20% reduction of Vmax at 1 Hz. The frequency-dependent reductions at these and higher concentrations were greatest for BUC, intermediate for NAD and least for NIF. These potencies at certain frequencies were, as a whole, consistent with log P-potency relationship established in our previous papers (Harada et al. 1981; Ban et al. 1985). The reductions of Vmax in APs in response to premature stimuli during basic stimuli at the rate of 0.25 or 0.027 Hz decayed exponentially during diastolic intervals (DI). The time constants of these decay process (tau) estimated by linear and nonlinear regression analyses and by eye were 12.2-9.6 s for BUC (50-100 mumol/l) and 2.9-4.8 s for NAD (1-2 mmol/l) and 57-87 ms for NIF (0.2-1 mmol/l). In terms of the molecular weight (MW)-log tau relationship (Ban et al. 1985), these tau values are within the 95% fiducial limit for BUC and NAD and deviated from the lower fiducial limit for NIF. The frequency-dependent reductions of Vmax by these drugs were explained in terms of a function of tau and the intercept Ao. Based on the study made by Cohen et al.(ABSTRACT TRUNCATED AT 250 WORDS)
M Ichiyama; S Sada; Y Takahashi; H Sada; T Ban
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Publication Detail:
Type:  In Vitro; Journal Article    
Journal Detail:
Title:  Naunyn-Schmiedeberg's archives of pharmacology     Volume:  332     ISSN:  0028-1298     ISO Abbreviation:  Naunyn Schmiedebergs Arch. Pharmacol.     Publication Date:  1986 Mar 
Date Detail:
Created Date:  1986-06-27     Completed Date:  1986-06-27     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0326264     Medline TA:  Naunyn Schmiedebergs Arch Pharmacol     Country:  GERMANY, WEST    
Other Details:
Languages:  eng     Pagination:  297-304     Citation Subset:  IM    
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MeSH Terms
Action Potentials / drug effects
Adrenergic beta-Antagonists / pharmacology*
Ethanolamines / pharmacology*
Guinea Pigs
Lipids / analysis
Myocardial Contraction / drug effects*
Papillary Muscles / drug effects*,  physiology
Propanolamines / pharmacology*
Time Factors
Reg. No./Substance:
0/Adrenergic beta-Antagonists; 0/Ethanolamines; 0/Lipids; 0/Propanolamines; 42200-33-9/Nadolol; 5054-57-9/nifenalol; 58409-59-9/bucumolol

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