Beta-receptors in resistance to phosphaturic effect of PTH in respiratory alkalosis.
Respiratory alkalosis results in a resistance to the phosphaturic effect of parathyroid hormone (PTH) and dibutyryl adenosine 3',5'-cyclic monophosphate (cAMP). The present studies evaluated the role of the beta-adrenergic system in that resistance phenomenon. In clearance experiments on acutely thyroparathyroidectomized male Wistar rats, respiratory alkalosis blunted the PTH-mediated increase in absolute and fractional excretion of phosphate (FEPi). Propranolol infusion restored the phosphaturic response to PTH:FEPi, 0.8 +/- 0.3 vs. 8.1 +/- 2.5% (P less than 0.005). Similarly, the increase of FEPi during cAMP infusion was also diminished by respiratory alkalosis: FEPi, 15.5 +/- 2.2 vs. 5.5 +/- 1.1% (P less than 0.005). This hypophosphaturic effect of respiratory alkalosis in the presence of cAMP was not observed in rats infused with propranolol compared with the period of normal ventilation: FEPi, 21.1 +/- 1.7 vs. 15.3 +/- 1.6 (P less than 0.02). Also, during the infusion of the highly selective beta 2-adrenoceptor antagonist, ICI 118,551, cAMP was phosphaturic in respiratory alkalosis compared with FEPi in the absence of the antagonist: FEPi, 13.0 +/- 2.5 vs. 5.5 +/- 1.1% (P less than 0.02). Finally, the infusion of the beta 2-agonist, fenoterol, to the normally ventilated rats significantly decreased FEPi in cAMP-infused rats in comparison to the absence of the agonist: FEPi, 4.0 +/- 0.7 vs. 22.1 +/- 2.6% (P less than 0.001). We conclude that the resistance to the phosphaturic effect of PTH and cAMP in respiratory alkalosis is mediated by beta-adrenoceptors.
Hoppe
A
A
Department of Clinical Biochemistry, Medical Academy, Gdańsk, Poland.
Rybczyńska
A
A
Knox
F G
FG
Angielski
S
S
D000471:Alkalosis / Q000503:physiopathology*; D000818:Animals; D000242:Cyclic AMP / Q000494:pharmacology; D005280:Fenoterol / Q000494:pharmacology*; D007668:Kidney / Q000187:drug effects / Q000502:physiology* / Q000503:physiopathology; D008297:Male; D010280:Parathyroid Glands / Q000502:physiology; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D010710:Phosphates / Q000652:urine*; D011433:Propranolol / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000502:physiology*; D012016:Reference Values; D019379:Teriparatide; D013965:Thyroidectomy
D010281:Parathyroid Hormone; D010446:Peptide Fragments; D010710:Phosphates; D011943:Receptors, Adrenergic, beta; D019379:Teriparatide; D005280:Fenoterol; D011433:Propranolol; D000242:Cyclic AMP