ISSN:
1573-7446
Keywords:
β-adrenoceptors
;
double-muscled calves
;
muscarinic receptors
;
smooth muscle
;
trachea
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract The total muscarinic (M1 + M2 + M3) and β-adrenergic receptors in the tracheal smooth muscle of conventional and double-muscled calves were identified and characterized with the non-specific antagonists [3H]quinuclidinyl benzilate ([3H]QNB) and [3H]dihydroalprenolol ([3H]DHA) respectively. Although the quantity of β-adrenoceptors in double-muscled calves was 25% lower (p〈0.05) than in conventional calves (B max=327±89 fmol/mg protein), adenylate cyclase assays indicated that the basal adenylate cyclase activity and the (−)-isopropylnoradrenaline (ISO)- and sodium fluoride (NaF)-stimulated values were not significantly different between these calves. However, the density of muscarinic receptors in double-muscled calves was 40% higher (p〈0.01) than in conventional calves (B max=2955±625 fmol/mg protein). Subtypes of muscarinic receptors were studied with [3H]telenzepine (M1-receptors), [3H]AF-DX 384 (M2-receptors) and [3H]4DAMP (M1 and M3-receptors). It was found that in both double-muscled and conventional calves about 40% of the receptors were of the M3-subtype, the remaining 60% being M2-receptors. From these results, it is suggested that inflammation of the respiratory tract in double-muscled calves may be complicated by an imbalance between the cholinergic bronchoconstrictor and the β-adrenergic bronchodilator components of the autonomic nervous system.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01839024
Permalink
