The mechanisms underlying heart stimulation by dopamine, with special reference to direct and indirect β adrenoceptor stimulation

Habuchi, Yoshizumi; Tanaka, Hideo; Yamamoto, Taku; Komori, Toshiaki; Nishio, Manabu; Yoshimura, Manabu

doi:10.3109/10641969709080811

Cited by 6 publications

(7 citation statements)

References 9 publications

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“…After denervation with reserpine or 6-OHDA, the effect of DA was greatly suppressed (Fig. 6B), indicating that the positive chronotropic effect of DA is primarily an indirect one via the release of NA from the sympathetic nerve terminals in the cardiac muscles, as reported previously [8,12,13].…”

Section: Dosesupporting

confidence: 84%

“…6B, DA produced significant dose-related increases in HR in the normal preparation. This positive chronotropic effect of DA was reported to be produced via β-adrenoceptor [12,35]. After denervation with reserpine or 6-OHDA, the effect of DA was greatly suppressed (Fig.…”

Section: Dosementioning

confidence: 80%

“…A chemical denervation of the sympathetic nerve terminals was made by a pretreatment of the animals with reserpine [7][8][9][10][11][12] or 6-OHDA [13][14][15], the former being dissolved in 20% ascorbic acid solution and given intraperitoneally at doses of 2 to 8 mg/kg body weight 24 h before isolation of the heart, and the latter by an intravenous injection at the ear vein at doses of 50 to 100 mg/kg body weight 24 h before isolation or by repeated injections, once a day for 2 days, at a dose of 50 mg/kg body weight. In each isolated heart it was determined that the pretreatments produced complete chemical denervations of the sympathetic nerve terminals, when there was no change in the HR and contraction forces in response to tyramine (Ty) applied to the perfusate.…”

Section: Methodsmentioning

confidence: 99%

“…To clarify whether these inotropic effects of DA as well as the chronotropic ones are direct actions on the cardiac muscles or indirect ones by releasing noradrenaline (NA) from the sympathetic nerve terminals in the cardiac muscles, the sympathetically denervated preparations by the treatments with reserpine [7][8][9][10][11][12] or 6-hydroxydopamine (6-OHDA) [13][14][15] were used, as reported previously. To the author's knowledge, it remains unknown whether the arrhythmogenic effects of DA could be produced by the direct or indirect actions.…”

mentioning

confidence: 99%

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Inotropic, Chronotropic, and Arrhythmogenic Effects of Dopamine on the Isolated Working Heart of Rabbit

Wakita¹

2007

J. Physiol. Sci

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Some improvements of Kodama's method for perfusing the isolated rabbit heart in its working mode were made. Increases in the right and left atrium pressure, together with an increase in the pulmonary artery pressure, were observed to occur immediately after the start of venous return, and then all of the increased pressures were found to remain at each constant level. In these stable states, the administration of dopamine (DA) into the perfusate was found to produce dose-related increases in contractile activities. In the preparations denervated with reserpine or 6-hydroxydopamine, in which tyramine (Ty) produced no response, the inotropic effectiveness of DA did not differ from that in the normal ones. On the other hand, responses to noradrenaline (NA) were found to increase significantly after the denervation. DA produced a dose-related increase in heart rates in the normal preparation, and this effect was greatly suppressed in the denervated preparations, suggesting that the primary chronotropic effect of DA is an indirect one via the release of NA from the sympathetic nerve terminals. Arrhythmogenic effects of NA, Ty or DA were also observed in these preparations. At all the doses tested, the incidence rates by NA were as high as 50% or more, the type of arrhythmia being recognized as atrial or ventricular extrasystole from the ECG analysis. On the other hand, the rates by DA were relatively low, less than 34%. From a comparison of the incidence rates between the normal and denervated preparations, this effect of DA was considered to be primarily an indirect one.Key words: isolated rabbit heart, perfusion method, inotropic effect of dopamine, chronotropic effect of dopamine, arrhythmogenic effect of dopamine.In regard to the methods for perfusing isolated mammalian heart preparations, Langendorff's is well known and has been used for more than 100 years for cardiovascular research in physiological, biochemical and/or pharmacological aspects [1,2]. In a heart perfused with this method, the retrograde perfusion via the cannulated aorta is designed to produce a constant flow or constant pressure in the aorta with no outflow or only mere outflow from the right or left ventricle, and there is no venous return except for a quite small amount of perfusate drainage via the coronary sinus to the right or left atrium. In this respect, Langendorff's preparation is not working.Kodama in 1961 attempted to convert the isolated rabbit heart preparation into a working mode by constructing an artificial venous and arterial circulation system using silicon and glass tubes and perfusing the heart via the vena cava and pulmonary vein to keep sufficient venous return to the ventricles [3][4][5][6]. In a heart thus perfused with a venous and arterial circulation system that is similar to that in vivo, the simultaneous recordings of perfusate pressures at the various parts of veins and arteries were possible, and it was recognized that the pressure of either the right or left ventricle exceeds that of the pulmonary or ao...

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Section: Dosesupporting

confidence: 84%

Section: Dosementioning

confidence: 80%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Inotropic, Chronotropic, and Arrhythmogenic Effects of Dopamine on the Isolated Working Heart of Rabbit

Wakita¹

2007

J. Physiol. Sci

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“…Theoretical and empirical studies support the validity of the use of HR as an index of BAS activity (Arnett and Newman, 2000;Fowles et al, 1982;Tranel et al, 1982). It is thought that the mechanisms underlying heart rate stimulation by dopamine involves direct and indirect (through norepinephrine release) stimulation of b adrenoceptors (Habuchi et al, 1997). Further support for the role of dopamine in the stimulating effects of alcohol intoxication is found in a study by Enggasser and deWit (2001), in which the stimulating effects of alcohol in a subgroup of individuals were dampened by a low dose of a dopamine antagonist, haloperidol.…”

mentioning

confidence: 95%