Parathyroid Ca(2+)-conducting currents are modulated by muscarinic receptor agonists and antagonists.

Chang, W (author)

Chen, T H (author)

Pratt, S A (author)

Yen, B (author)

Fu, Michael, 1963 (author): Gothenburg University,Göteborgs universitet,Wallenberglaboratoriet,Wallenberg Laboratory

Shoback, D (author)

(creator_code:org_t)

Abstract Subject headings

Parathyroid cells express Ca(2+)-conducting cation currents, which are activated by raising the extracellular Ca2+ concentration ([Ca2+]o) and blocked by dihydropyridines. We found that acetylcholine (ACh) inhibited these currents in a reversible, dose-dependent manner (50% inhibitory concentration approximately equal to 10(-8) M). The inhibitory effects could be mimicked by the agonist (+)-muscarine. The effects of ACh were blunted by the antagonist atropine and reversed by removing ATP from the pipette solution (+)-Muscarine enhanced the adenosine 3',5'-cyclic monophosphate (cAMP) production by 30% but had no effect on inositol phosphate accumulation in parathyroid cells. Oligonucleotide primers, based on sequences of known muscarinic receptors (M1-M5), were used in reverse transcriptase-polymerase chain reaction (RT-PCR) to amplify receptor cDNA from parathyroid poly (A)+ RNA. RT-PCR products displayed > 90% nucleotide sequence identity to human M2- and M4-receptor cDNAs. Expression of M2-receptor protein was further confirmed by immunoblotting and immunocytochemistry. Thus parathyroid cells express muscarinic receptors of M2 and possibly M4 subtypes. These receptors may couple to dihydropyridine-sensitive, cation-selective currents through the activation of adenylate cyclase and ATP-dependent pathways in these cells.

MEDICIN OCH HÄLSOVETENSKAP -- Medicinska och farmaceutiska grundvetenskaper -- Fysiologi (hsv//swe)
MEDICAL AND HEALTH SCIENCES -- Basic Medicine -- Physiology (hsv//eng)

By the author/editor: Chang, W; Chen, T H; Pratt, S A; Yen, B; Fu, Michael, 196 ...; Shoback, D

About the subject

MEDICAL AND HEALTH SCIENCES: MEDICAL AND HEAL ...; and Basic Medicine; and Physiology

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