In vivo induced desensitization of beta-adrenoceptors in rat lung. Effect of nitrendipine.
The effect of nitrendipine on desensitization of beta-adrenoceptors induced by isoprenaline was investigated using rat lungs. Rats were treated with saline, isoprenaline, nitrendipine, or nitrendipine + isoprenaline. After 7 days of treatment, tracheas were isolated and the dissociation constant (Kb) for the propranolol-beta-receptor complex was determined. Lung parenchymal tissue was used to study the binding characteristics of beta-adrenoceptors. The Kb value for the propranolol-beta-receptor complex was found to be up to 6.4-fold higher in trachea isolated from isoprenaline-treated rats (32 +/- 5.4 nM) than from control rats (4.9 +/- 1.2 nM); the Kb value for trachea from isoprenaline + nitrendipine-treated rats was 7.0 +/- 1.2 nM. A 31% reduction in the number of beta-adrenoceptors as compared to those of the control group was observed in the isoprenaline-treated group while the number of the beta-adrenoceptors in the isoprenaline + nitrendipine-treated group was significantly increased as compared to that of the isoprenaline-treated group.
Vassilev
P P
PP
Institute of Physiology, Bulgarian Academy of Sciences, Sofia, Bulgaria.
Danchev
N
N
Staneva-Stoytcheva
D
D
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002217:Carbachol / Q000494:pharmacology; D004347:Drug Interactions; D007545:Isoproterenol / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D008168:Lung / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D009568:Nitrendipine / Q000494:pharmacology*; D010277:Parasympathomimetics / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011943:Receptors, Adrenergic, beta / Q000187:drug effects* / Q000378:metabolism; D013566:Sympathomimetics / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects* / Q000378:metabolism
D000319:Adrenergic beta-Antagonists; D002121:Calcium Channel Blockers; D010277:Parasympathomimetics; D011943:Receptors, Adrenergic, beta; D013566:Sympathomimetics; D002217:Carbachol; D009568:Nitrendipine; D011433:Propranolol; D007545:Isoproterenol