Endothelial cell-dependent relaxation and contraction induced by histamine in the isolated guinea-pig pulmonary artery.
Histamine (10(-8)-10(-6) M) relaxed in a concentration-dependent manner the guinea-pig pulmonary artery which had been contracted by noradrenaline (5 X 10(-7) M). After the removal of endothelial cells (ETCs) histamine at the same concentrations did not cause relaxation but induced additional contraction. Both responses to histamine were antagonized by chlorpheniramine (3 X 10(-7) M). These results suggest that in the pulmonary artery histamine simultaneously stimulates H1-receptors located on both ETCs and smooth muscle cells. This results in two opposite effects, relaxation mediated by ETCs, and contraction.
D000818:Animals; D002744:Chlorpheniramine / Q000494:pharmacology; D004727:Endothelium / Q000502:physiology; D005260:Female; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009126:Muscle Relaxation / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D009638:Norepinephrine / Q000494:pharmacology; D011651:Pulmonary Artery / Q000502:physiology
D002744:Chlorpheniramine; D006632:Histamine; D009638:Norepinephrine