title: Possible Role of TRP Channels in Rat Glomus Cells.
abstract: Carotid body (CB) glomus cells depolarize in response to hypoxia, causing a [Ca(2+)](i) increase, at least in part, through activation of voltage-dependent channels. Recently, Turner et al. (2013) showed that mouse glomus cells with knockout of TASK1/3(-/-) channels have near-normal [Ca(2+)](i) response to hypoxia. Thus, we postulated that TRP channels may provide an alternate calcium influx pathway which may be blocked by the TRP channel antagonist, 2-APB (2-aminoethoxydiphenylborane). We confirmed that 2-APB inhibited the afferent nerve response to hypoxia, as previously reported (Lahiri S, Patel G, Baby S, Roy A (2009) 2-APB mediated effects on hypoxic calcium influx in rat carotid body glomus cells. FASEB 2009, Abstract, LB157; Kumar P, Pearson S, Gu Y (2006) A role for TRP channels in carotid body chemotransduction? FASEB J 20:A12-29). To examine the mechanism for this inhibition, we examined dissociated rat CB glomus cells for [Ca(2+)](i) responses to hypoxia, anoxia (with sodium dithionite), 20 mM K(+), NaSH, NaCN, and FCCP in absence/presence of 2-APB (100 μM). Also the effect of 2-APB on hypoxia and/or anoxia were investigated on NADH and mitochondria (MT) membrane potential. Our findings are as follows: (1) 2-APB significantly blocked the [Ca(2+)](i) increase in response to hypoxia and anoxia, but not the responses to 20 mM K(+). (2) The [Ca(2+)](i) responses NaSH, NaCN, and FCCP were significantly blocked by 2-APB. (3) Hypoxia-induced increases in NADH/NAD(+) and MT membrane depolarization were not effected by 2-APB. Thus TRP channels may provide an important pathway for calcium influx in glomus cells in response to hypoxia.
authors: Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, USA, kiminsook@uams.edu.
authors: Insook
authors: I
authors: Kim
authors: Lasha
authors: L
authors: Fite
authors: David F
authors: DF
authors: Donnelly
authors: Jung H
authors: JH
authors: Kim
authors: John L
authors: JL
authors: Carroll
mesh_terms: D000818:Animals; D001896:Boron Compounds / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002344:Carotid Body / Q000166:cytology / Q000502:physiology*; D005260:Female; D008297:Male; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000502:physiology; D009243:NAD / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D050051:Transient Receptor Potential Channels / Q000502:physiology*
chemical_list: C504876:2-aminoethoxydiphenylborane; D001896:Boron Compounds; D050051:Transient Receptor Potential Channels; D009243:NAD; D002118:Calcium