TY - JOUR
T1 - Vascular effects of long-term propranolol administration after chronic nitric oxide blockade
AU - Priviero, Fernanda B.M.
AU - Teixeira, Cleber E.
AU - Claudino, Mário A.
AU - Nucci, Gilberto De
AU - Zanesco, Angelina
AU - Antunes, Edson
N1 - Funding Information:
Fernanda B.M. Priviero and Edson Antunes are grateful to Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) for financial support.
PY - 2007/10/1
Y1 - 2007/10/1
N2 - Long-term propranolol treatment reduces arterial blood pressure in hypertensive individuals mainly by reducing peripheral vascular resistance, but mechanisms underlying their vasodilatory effect remain poorly investigated. This study aimed to investigate whether long-term propranolol administration ameliorates the impairment of relaxing responses of aorta and mesenteric artery from rats made hypertensive by chronic nitric oxide (NO) deficiency, and underlying mechanisms mediating this phenomenon. Male Wistar rats were treated with Nω-Nitro-l-arginine methyl ester (l-NAME; 20 mg/rat/day) for four weeks. dl-Propranolol (30 mg/rat/day) was given concomitantly to l-NAME in the drinking water. Treatment with l-NAME markedly increased blood pressure, an effect largely attenuated by dl-propranolol. In phenylephrine-precontracted aortic rings, the reduction of relaxing responses for acetylcholine (0.001-10 μM) in l-NAME group was not modified by dl-propranolol, whereas in mesenteric rings the impairment of acetylcholine-induced relaxation by l-NAME was significantly attenuated by dl-propranolol. In mesenteric rings precontracted with KCl (80 mM), dl-propranolol failed to attenuate the impairment of acetylcholine-induced relaxation by l-NAME. The contractile responses to extracellular CaCl2 (1-10 mM) were increased in l-NAME group, and co-treatment with dl-propranolol reduced this response in both preparations in most Ca2+ concentrations used. The NO2/NO3 plasma levels and superoxide dismutase (SOD) activity were reduced in l-NAME-treated rats, both of which were significantly prevented by dl-propranolol. In conclusion, propranolol-induced amplification of the relaxation to acetylcholine in mesenteric arteries from l-NAME-treated rats is sensitive to depolarization. Additional mechanisms involving blockade of Ca2+ entry in the vascular smooth muscle and increase in NO bioavailability contributes to beneficial effects of long-term propranolol treatment.
AB - Long-term propranolol treatment reduces arterial blood pressure in hypertensive individuals mainly by reducing peripheral vascular resistance, but mechanisms underlying their vasodilatory effect remain poorly investigated. This study aimed to investigate whether long-term propranolol administration ameliorates the impairment of relaxing responses of aorta and mesenteric artery from rats made hypertensive by chronic nitric oxide (NO) deficiency, and underlying mechanisms mediating this phenomenon. Male Wistar rats were treated with Nω-Nitro-l-arginine methyl ester (l-NAME; 20 mg/rat/day) for four weeks. dl-Propranolol (30 mg/rat/day) was given concomitantly to l-NAME in the drinking water. Treatment with l-NAME markedly increased blood pressure, an effect largely attenuated by dl-propranolol. In phenylephrine-precontracted aortic rings, the reduction of relaxing responses for acetylcholine (0.001-10 μM) in l-NAME group was not modified by dl-propranolol, whereas in mesenteric rings the impairment of acetylcholine-induced relaxation by l-NAME was significantly attenuated by dl-propranolol. In mesenteric rings precontracted with KCl (80 mM), dl-propranolol failed to attenuate the impairment of acetylcholine-induced relaxation by l-NAME. The contractile responses to extracellular CaCl2 (1-10 mM) were increased in l-NAME group, and co-treatment with dl-propranolol reduced this response in both preparations in most Ca2+ concentrations used. The NO2/NO3 plasma levels and superoxide dismutase (SOD) activity were reduced in l-NAME-treated rats, both of which were significantly prevented by dl-propranolol. In conclusion, propranolol-induced amplification of the relaxation to acetylcholine in mesenteric arteries from l-NAME-treated rats is sensitive to depolarization. Additional mechanisms involving blockade of Ca2+ entry in the vascular smooth muscle and increase in NO bioavailability contributes to beneficial effects of long-term propranolol treatment.
KW - Arterial reactivity
KW - Endothelial dysfunction
KW - Endothelium-derived hyperpolarizing factor
KW - Nitric oxide bioavailability
KW - β-adrenoceptor antagonist
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U2 - 10.1016/j.ejphar.2007.05.060
DO - 10.1016/j.ejphar.2007.05.060
M3 - Article
C2 - 17610863
AN - SCOPUS:34548474532
SN - 0014-2999
VL - 571
SP - 189
EP - 196
JO - European Journal of Pharmacology
JF - European Journal of Pharmacology
IS - 2-3
ER -