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We studied the simultaneous alpha- and beta-adrenergic response characteristics of canine tracheal smooth muscle in 398 strips from 67 dogs in vitro. Experiments were performed to determine the effects of beta-adrenergic blockade on the expression of the alpha-adrenoceptor contractile responses elicited by norepinephrine (NE), phenylephrine (PE), and clonidine (CLO). Maximal active tension caused by NE increased from 39.1 +/- 27.0 to 241 +/- 75.0 g/cm2 as the concentration of propranolol (PROP) was increased from 10(-6) to 10(-4) M. Augmentation of tracheal smooth muscle contraction caused by PE and CLO was also observed with progressive beta-adrenoceptor blockade; contraction to NE, PE, and CLO was blocked selectively with 3 X 10(-5) M phentolamine (PA) and phenoxybenzamine (PBZ). The beta-adrenergic relaxing properties of the same three agonists were also studied. After alpha-adrenergic blockade with PA or PBZ, all three agonists caused relaxation (NE greater than CLO greater than PE) of methacholine-induced contraction of tracheal smooth muscle that was reversed selectively with PROP. We demonstrate that NE, PE, and CLO cause simultaneous stimulation of both the alpha- and beta-adrenergic receptors in tracheal smooth muscle; the net response elicited is the result of adrenergic physiological antagonism and depends on the relative degree of alpha- and/or beta-adrenoceptor blockade.
A R Leff, and
J Tallet, and
N M Munoz, and
N Shoulberg
November 1987,
Chinese medical journal,
A R Leff, and
J Tallet, and
N M Munoz, and
N Shoulberg
May 1998,
Nihon Kokyuki Gakkai zasshi = the journal of the Japanese Respiratory Society,
A R Leff, and
J Tallet, and
N M Munoz, and
N Shoulberg
January 1981,
European surgical research. Europaische chirurgische Forschung. Recherches chirurgicales europeennes,
A R Leff, and
J Tallet, and
N M Munoz, and
N Shoulberg
January 1974,
Surgical forum,
A R Leff, and
J Tallet, and
N M Munoz, and
N Shoulberg
June 1975,
Urology,
A R Leff, and
J Tallet, and
N M Munoz, and
N Shoulberg
August 1978,
Journal of applied physiology: respiratory, environmental and exercise physiology,
A R Leff, and
J Tallet, and
N M Munoz, and
N Shoulberg
December 1983,
The Journal of pharmacology and experimental therapeutics,
A R Leff, and
J Tallet, and
N M Munoz, and
N Shoulberg
January 1979,
Allergologia et immunopathologia,
A R Leff, and
J Tallet, and
N M Munoz, and
N Shoulberg
January 1985,
The American review of respiratory disease,
A R Leff, and
J Tallet, and
N M Munoz, and
N Shoulberg
May 1973,
Investigative urology,
