Effects of osmotic changes on the chemoreceptor cell of rat carotid body

Zoltán Molnár, Gábor L. Petheo, Csaba Fülöp, András Spät

Research output: Contribution to journalReview article

10 Citations (Scopus)

Abstract

The carotid body plays a crucial role in cardiorespiratory regulation. In the present study we investigated the effect of osmotic changes on cytoplasmic calcium concentration ([Ca2+]c) and pH (pHi) of isolated chemoreceptor cells of the rat carotid body. In CO2/HCO3--buffered medium, reduction of osmolality from the control level of 300 mosmol kg-1 to 250-285 mosmol kg-1 resulted in a rise in [Ca2+]c, as measured with Indo-1, whereas elevation of osmolality to 350 mosmol kg-1 had no effect. The Ca2+ response required extracellular Ca2+ and was reduced by application of the L-type Ca2+ channel antagonist nifedipine (10 μM). The hyposmosis-induced Ca2+ response could be prevented by application of niflumic acid (300 μM), an inhibitor of the swelling-activated Cl- channel. In whole-cell patch-clamp experiments niflumic acid abolished the swelling-activated Cl- current but only slightly depressed the Ca2+ current. The inhibition of Ca2+ current by niflumic acid does not account for its action in preventing of hyposmosis-induced Ca2+ response, which seems to be initiated by Cl--mediated depolarisation. Withdrawal of CO2/HCO3- also prevented the Ca2+ response. Reduction of the osmotic concentration by 50 mosmol kg-1 induced a small but sustained decrease in pHi, while elevation by 50 mosmol kg-1 had an inverse effect, as measured fluorimetrically with carboxy SNARF-1. Our conclusion is that in the rat chemoreceptor cell the activation of Cl- channels, e.g. by hyposmotic challenge, induces depolarisation, which, in turn, activates voltage-gated Ca2+ channels.

Original languageEnglish
Pages (from-to)471-481
Number of pages11
JournalJournal of Physiology
Volume546
Issue number2
DOIs
Publication statusPublished - Jan 15 2003

ASJC Scopus subject areas

  • Physiology

Fingerprint Dive into the research topics of 'Effects of osmotic changes on the chemoreceptor cell of rat carotid body'. Together they form a unique fingerprint.

  • Cite this