Dopamine relaxes porcine coronary arteries and stimulates potassium channel activity in porcine coronary arterial smooth muscle cells
The relaxing effect of dopamine on isolated coronary vessels and the activating effect of dopamine on large-conductance, calcium-activated potassium channels (BKCa) in the membrane of coronary myocytes were investigated with isometric tension recording method and patch-clamp technique. Tension studies demonstrated that dopamine relaxed prostaglandin F2Î±-induced contraction of porcine coronary arteries in a concentration-dependent manner, but it failed to relax high [K+] precontracted arteries. In cell attached patch experiments, dopamine caused a significant increase in the mean opening probability of the BKCa channels. The effect of dopamine was not blocked by propranolol but was completely prevented by SCH23390, a selective DA1 antagonist. These results demonstrate that dopamine relaxes prostaglandin F2Î±-induced contraction of porcine coronary arteries via activation of DA1 receptors which causes stimulation of BKCa channel activity.
Chinese Journal of Pharmacology and Toxicology
Han, Guichun; McMillin, J. P.; and White, Richard E., "Dopamine relaxes porcine coronary arteries and stimulates potassium channel activity in porcine coronary arterial smooth muscle cells" (2000). PCOM Scholarly Papers. 1099.