title: In vivo arteriolar dilation in response to parathyroid hormone fragments.
abstract: The in vivo responsiveness of small arterioles to the topical administration of two parathyroid hormone fragments was investigated using television microscopy. Male Sprague-Dawley rats were anesthetized with sodium pentobarbital (50 mg/kg) and second- and third-order arterioles in the cremaster muscle were exposed to increasing concentrations (2 X 10(-5) to 6 X 10(-4) mg/ml) of either hPTH (1-34) or bPTH-(3-34). Second- and third-order arterioles within the cremaster dilated (183% and 281% of control, respectively) following exposure to PTH-(1-34) in bath concentration of 10(-4) mg/ml and above. The dilation associated with PTH administration was abolished in second-order and greatly attenuated for third-order arterioles when the first two amino acid residues of the PTH molecule were removed (PTH (3-34) fragment). Inhibition of endogenous prostaglandins synthesis with mefenamic acid did not attenuate the vasodilator response to PTH. However, exposure to the muscarinic blocking agent atropine (10(-7) g/ml) totally inhibited the dilator response to PTH-(1-34). These data suggest that PTH induces arteriolar dilation by stimulation of muscarinic receptors in the vasculature possibly by causing the release of endogenous acetylcholine.
authors: Department of Physiology and Biophysics, University of Louisville, KY 40292.
authors: J P
authors: JP
authors: Dowe
authors: I G
authors: IG
authors: Joshua
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001160:Arterioles / Q000187:drug effects; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D008297:Male; D008528:Mefenamic Acid / Q000494:pharmacology; D009132:Muscles / Q000098:blood supply; D010281:Parathyroid Hormone / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D011453:Prostaglandins / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D012039:Regional Blood Flow / Q000187:drug effects; D019379:Teriparatide; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D010281:Parathyroid Hormone; D010446:Peptide Fragments; D011453:Prostaglandins; D019379:Teriparatide; D008528:Mefenamic Acid; C031617:parathyroid hormone (3-34); D001285:Atropine; D000109:Acetylcholine