1980
DOI: 10.1111/j.1476-5381.1980.tb07905.x
|View full text |Cite
|
Sign up to set email alerts
|

Α‐sympathomimetic Amines and Calcium‐mediated Action Potentials in Guinea‐pig Ventricular Muscle

Abstract: 1 The ability of amines, having ca-or a-and f-adrenoceptor stimulating activity, to restore excitability and contractility in heart preparations partially depolarized by potassium, was investigated in guinea-pig ventricular muscle in order to elucidate the mechanism of the positive inotropic effect mediated via a-adrenoceptors. 2 In preparations in which fast sodium channels were inactivated by K+-rich medium (22 mM) slow electrical responses as well as contractions were consistently induced by high concentrat… Show more

Help me understand this report

Search citation statements

Order By: Relevance

Paper Sections

Select...
2
1
1

Citation Types

1
7
0

Year Published

1982
1982
2006
2006

Publication Types

Select...
7
2

Relationship

1
8

Authors

Journals

citations
Cited by 34 publications
(8 citation statements)
references
References 29 publications
1
7
0
Order By: Relevance
“…Again these properties are shared by isoprenaline [17] and are in good agreement with the hypothesis of a cAMPmediated inotropic effect: more particularly, the increase in the rate of relaxation and the ability of the inotropic effect to follow high frequencies of stimulation can be adequately explained by a cAMP-stimulated calcium uptake by the sarcotubular system [28]. With regard to the characteristics of the Hi-receptor-mediated inotropie effect it is apparent that, owing to the lack of specificity of PEA at high doses [23], they must be inferred from the effects induced by PEA concentrations up to 10-5-3 x 10 -5 M. Our findings interestingly indicate that PEA, at these concentrations, showed properties very similar to those previously demonstrated with alpha tamine H t receptors is chiefly due to an enhanced adl"enoceptor agonists [17,29,30] which also are release of calcium from the sarcotubular system. known to be capable of inducing a cAMP-…”
Section: Discussionsupporting
confidence: 81%
“…Again these properties are shared by isoprenaline [17] and are in good agreement with the hypothesis of a cAMPmediated inotropic effect: more particularly, the increase in the rate of relaxation and the ability of the inotropic effect to follow high frequencies of stimulation can be adequately explained by a cAMP-stimulated calcium uptake by the sarcotubular system [28]. With regard to the characteristics of the Hi-receptor-mediated inotropie effect it is apparent that, owing to the lack of specificity of PEA at high doses [23], they must be inferred from the effects induced by PEA concentrations up to 10-5-3 x 10 -5 M. Our findings interestingly indicate that PEA, at these concentrations, showed properties very similar to those previously demonstrated with alpha tamine H t receptors is chiefly due to an enhanced adl"enoceptor agonists [17,29,30] which also are release of calcium from the sarcotubular system. known to be capable of inducing a cAMP-…”
Section: Discussionsupporting
confidence: 81%
“…These and the present results suggest that the positive inotropic effect of phenylephrine in the presence of propranolol, at least in rabbit and cattle, is mediated by a-adrenoceptors and that it is probably related to an increase in the slow calcium inward current. However, contradictory results were reported by Ledda et al (1980) and Sanchez-Chapula (1981) who found that the effects of phenylephrine on slow action potentials in guinea-pig papillary muscles were completely abolished by P-blocking agents. These discrepancies do not necessarily contradict the conclusion drawn above; they are more likely to be due to species differencies.…”
Section: Voltage Clamp Experimentsmentioning
confidence: 87%
“…Although it has been proposed that a, agonists increase , others have suggested that the predominant effect is not an increase in ICa (24,25) but, rather, a reduction in time-independent (26) or timedependent (27, 28) …”
Section: Introductionmentioning
confidence: 99%
“…Although it has been proposed that a, agonists increase ICa (20)(21)(22)(23), others have suggested that the predominant effect is not an increase in ICa (24,25) but, rather, a reduction in time-independent (26) or timedependent (27,28) Pharmacologic agents were applied by pressure ejection from 1-to 3-,um "puffer" pipettes placed within =25 ,um of the cell surface. A PMA stock solution was prepared at 1 mM in dimethyl sulfoxide, aliquoted, and stored under N2 at -70°C; the PDA stock was 0.1 mM in dimethyl sulfoxide.…”
mentioning
confidence: 99%