[Effects of dopamine on the coronary vessels of swine].
The pharmacological responses of dopamine, a catecholamine which is used as a circulatory active drug in shock treatment, were investigated in isolated coronary arteries of pigs from the slaughter house. The effects are compared with those obtained after application of adrenaline and noradrenaline in the same in vitro system. The aim of the experiments was to discover whether the three catecholamines have an effect on the same adrenergic receptors and to characterize the specific effect of dopamine. Phentolamine and propranolol were used as adrenergic alpha- und beta-blockers, azaperone and haloperidol were used as unspecific antagonists, and domperidone as a specific dopamine antagonist. The three catecholamines caused a dose-dependent vasodilation of the coronary artery. A pretreatment of the vessels with phentolamine did not affect the vasodilation after all three catecholamines. Propranolol inhibited the effects of only adrenaline and noradrenaline, but not those of dopamine. Azaperone, haloperidol and domperidone were effective to inhibit the dopamine-action, but not those of adrenaline and noradrenaline. The results show, that the vasodilation of the coronary artery by dopamine is not related to a stimulation of adrenergic alpha- oder beta-receptors. Adrenaline and noradrenaline produce a vasodilation only by a stimulation of adrenergic beta-receptors, as alpha-receptors are not present in the coronary system of the pig. The conclusion is that the vasodilation of the coronary artery is caused by a stimulation of specific dopaminergic receptors. The coronary effects of dopamine in shock therapy are reduced after a treatment of the animals with butyrophenone derivatives like azaperone or haloperidol or after treatment with the specific dopamine antagonist domperidone.(ABSTRACT TRUNCATED AT 250 WORDS)
Hapke
H J
HJ
Institut für Pharmakologie, Toxikologie und Pharmazie, Tierärztlichen Hochschule Hannover.
Höll
C
C
D000818:Animals; D003331:Coronary Vessels / Q000187:drug effects*; D046508:Culture Techniques; D004298:Dopamine / Q000494:pharmacology*; D004837:Epinephrine / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D013552:Swine / Q000502:physiology*; D014664:Vasodilation / Q000187:drug effects*
D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine
Dopaminwirkungen auf die Koronargefässe des Schweines.