Effect of beta-antagonists on isoprenaline-induced secretion of fluid, amylase and protein by the parotid gland of the red kangaroo, Macropus rufus.
Selective and non-selective beta-adrenoceptor antagonists were used to block the increases in fluid, protein and amylase secretion caused by sympathomimetic stimulation of the parotid gland of red kangaroos during intracarotid infusion of isoprenaline. ICI118551 at antagonist/agonist ratios up to 300:1 caused increasing but incomplete blockade of fluid secretion, and protein/amylase release. Atenolol at antagonist/agonist ratios up to 300:1 was only marginally more potent than ICI118551 at blocking the fluid, protein and amylase responses. Propranolol at antagonist/agonist ratios of 30:1 was as effective at blocking fluid and protein secretion as the highest ratios of either atenolol or ICI118551. Simultaneous administration of atenolol (30:1) with ICI118551 (30:1) was not as potent as propranolol (30:1). Thus, the beta-adrenoceptor/s in the acini of the kangaroo parotid gland appear to have antagonist-binding affinities atypical of those found for eutherian tissues. The data are consistent with the gland possessing either a single anomalous beta-adrenoceptor or functional beta(2)-receptors in addition to the beta(1)-receptors which are characteristic of eutherian salivary glands.
Beal
A M
AM
School of Biological Science, University of New South Wales, 2052, Sydney, Australia. m.beal@unsw.edu.au
D000109:Acetylcholine / Q000008:administration & dosage; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000681:Amylases / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D001262:Atenolol / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D007545:Isoproterenol / Q000494:pharmacology; D007614:Macropodidae / Q000378:metabolism*; D008297:Male; D010306:Parotid Gland / Q000187:drug effects* / Q000378:metabolism*; D011412:Propanolamines / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011506:Proteins / Q000187:drug effects / Q000378:metabolism*; D012463:Saliva / Q000187:drug effects / Q000378:metabolism
D000318:Adrenergic beta-Agonists; D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; D011506:Proteins; C026777:ICI 118551; D001262:Atenolol; D011433:Propranolol; D000681:Amylases; D007545:Isoproterenol; D000109:Acetylcholine