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Am J Physiol Endocrinol Metab 273: E880-E890, 1997;
0193-1849/97 $5.00
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Vol. 273, Issue 5, E880-E890, November 1997

Parathyroid Ca2+-conducting currents are modulated by muscarinic receptor agonists and antagonists

Wenhan Chang1, Tsui-Hua Chen1, Stacy A. Pratt1, Benedict Yen2, Michael Fu3, and Dolores Shoback1

1 Endocrine Research Unit, Department of Medicine and 2 Department of Pathology, Veterans Affairs Medical Center, University of California, San Francisco, California 94121; and 3 Wallenberg Laboratory, Goteborgs University, Gothenburg, Sweden S-41345

Parathyroid cells express Ca2+-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 approx 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.

calcium currents; calcium channel; calcium receptor; adenylate cyclase; adenosine 3',5'-cyclic monophosphate


This article has been cited by other articles:


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 Am. J. Physiol. Endocrinol. Metab.Home page
W. Chang, S. A. Pratt, T.-H. Chen, C.-L. Tu, G. Mikala, A. Schwartz, and D. Shoback
Parathyroid cells express dihydropyridine-sensitive cation currents and L-type calcium channel subunits
Am J Physiol Endocrinol Metab, July 1, 2001; 281(1): E180 - E189.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Endocrinol. Metab.Home page
W. Chang, T.-H. Chen, S. Pratt, and D. Shoback
Regulation of extracellular calcium-activated cation currents by cAMP in parathyroid cells
Am J Physiol Endocrinol Metab, August 1, 1998; 275(2): E213 - E221.
[Abstract] [Full Text] [PDF]


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