TY - JOUR
T1 - Reversal of α-adrenoceptor blockade by propranolol in isolated rat pulmonary artery
AU - Abdelrahman, Aly
AU - Nguyen, Hoang
AU - Pang, Catherine C.Y.
N1 - Funding Information:
This work was supported by the Medical Research Council of Canada. Dr. Aly Abdelrahman was a recipient of a B.C. Heart Foundation research traineeship. Ms Hoang Nguyen was a recipient of a B.C. Heart Foundation undergraduate summer research traineeship. The authors would like to thank Imperial Chemical Industry, U.K. for the supply of ICI 118,551 HC1 and Ciba Pharmaceuticals, U.S.A. for the supply of phentolamine HCI.
PY - 1990/5/31
Y1 - 1990/5/31
N2 - Pulmonary artery rings were prepared from rats (group I to VI, n = 5-7 per group) in order to investigate if a β-adrenoceptor antagonist interferes with the effect of α-adrenoceptor blockade. In I, four cumulative noradrenaline (NA) dose-response curves (10-9 to 10-3 M) were constructed. In II, NA curves were constructed first, without blockers, then in the presence of phentolamine (10-6 M), then phentolamine plus propranolol (10-8 M). III, IV and V were treated similar to II, except that atenolol (10-8 M), ICI 118,551 (10-8 M) and propranolol (10-6 M), respectively, were added instead of propranolol (10-8 M). In VI, NA (10-6 M) was added followed by phentolamine and then propranolol (10-9 to 10-6 M). Phentolamine shifted the NA curve to the right with an increase in the EC50 value. Propranolol but not atenolol or ICI 118,551, reduced the elevated EC50 values caused by phentolamine. In group VI, the increase in force by NA was reduced by phentolamine; the effect of phentolamine was completely abolished by propranolol. Thus, propranolol interferes with the effect of phentolamine in the rat pulmonary artery.
AB - Pulmonary artery rings were prepared from rats (group I to VI, n = 5-7 per group) in order to investigate if a β-adrenoceptor antagonist interferes with the effect of α-adrenoceptor blockade. In I, four cumulative noradrenaline (NA) dose-response curves (10-9 to 10-3 M) were constructed. In II, NA curves were constructed first, without blockers, then in the presence of phentolamine (10-6 M), then phentolamine plus propranolol (10-8 M). III, IV and V were treated similar to II, except that atenolol (10-8 M), ICI 118,551 (10-8 M) and propranolol (10-6 M), respectively, were added instead of propranolol (10-8 M). In VI, NA (10-6 M) was added followed by phentolamine and then propranolol (10-9 to 10-6 M). Phentolamine shifted the NA curve to the right with an increase in the EC50 value. Propranolol but not atenolol or ICI 118,551, reduced the elevated EC50 values caused by phentolamine. In group VI, the increase in force by NA was reduced by phentolamine; the effect of phentolamine was completely abolished by propranolol. Thus, propranolol interferes with the effect of phentolamine in the rat pulmonary artery.
KW - Pulmonary artery
KW - Smooth muscle
KW - α-Adrenoceptors
KW - β-Adrenoceptor antagonists
KW - β-Adrenoceptors
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U2 - 10.1016/0014-2999(90)90247-4
DO - 10.1016/0014-2999(90)90247-4
M3 - Article
C2 - 1974860
AN - SCOPUS:0025351234
SN - 0014-2999
VL - 181
SP - 83
EP - 88
JO - European Journal of Pharmacology
JF - European Journal of Pharmacology
IS - 1-2
ER -