Contraction and relaxation responses of femoral artery and aorta to norepinephrine in young rats.
1. In femoral artery of 3-week-old rats, norepinephrine (NE) at 1 nM-0.1 microM concentration-dependently produced a contraction but, at higher concentrations (0.3-30 microM), NE relaxed the tissue. 2. In aorta of the 3-week-old rat, NE elicited a contraction at 1 nM to 0.3 microM and a relaxation at 1 microM and higher. 3. The magnitude of the NE-induced relaxation in the aorta was much less than that in the femoral artery. 4. Atenolol (a beta(1)-selective antagonist) modulated these NE responses in the femoral artery and butoxamine (a beta(2)-selective antagonist) in the aorta. 5. Subcutaneous application of propranolol and isoproterenol for 10 days in 4-week-old rats sensitized and desensitized the NE-induced relaxation, respectively. 6. It is suggested that, in the young rat, beta(1)- and beta(2)-adrenoceptors contribute the NE-induced relaxation in the femoral artery and aorta, respectively, and that beta-adrenoceptors may contribute to the limitation of NE-induced vasoconstriction in certain types of vascular beds.
Fujimoto
S
S
Department of Pharmacology, Nagoya City University Medical School, Japan.
Itoh
T
T
D058671:Adrenergic beta-1 Receptor Antagonists; D058672:Adrenergic beta-2 Receptor Antagonists; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000502:physiology; D001262:Atenolol / Q000494:pharmacology; D002078:Butoxamine / Q000494:pharmacology; D005263:Femoral Artery / Q000187:drug effects / Q000502:physiology; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009126:Muscle Relaxation / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D009638:Norepinephrine / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar
D058671:Adrenergic beta-1 Receptor Antagonists; D058672:Adrenergic beta-2 Receptor Antagonists; D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D002078:Butoxamine; D001262:Atenolol; D011433:Propranolol; D007545:Isoproterenol; D009638:Norepinephrine