期刊
PFLUGERS ARCHIV-EUROPEAN JOURNAL OF PHYSIOLOGY
卷 463, 期 5, 页码 743-754出版社
SPRINGER HEIDELBERG
DOI: 10.1007/s00424-012-1089-8
关键词
Hydrogen sulphide; Calcium signalling; Chemoreceptors; Mitochondrial function; Oxygen sensing
类别
资金
- Medical Research Council [G1001134] Funding Source: researchfish
- MRC [G1001134] Funding Source: UKRI
It has been proposed that endogenous H2S mediates oxygen sensing in chemoreceptors; this study investigates the mechanisms by which H2S excites carotid body type 1 cells. H2S caused a rapid reversible increase in intracellular calcium with EC50 approximate to 6 mu M. This [Ca2+](i) response was abolished in Ca-free Tyrode. In perforated patch current clamp recordings, H2S depolarised type 1 cells from -59 to -35 mV; this was accompanied by a robust increase in [Ca2+](i). Voltage clamping at the resting membrane potential abolished the H2S-induced rise in [Ca2+](i). H2S inhibited background K+ current in whole cell perforated patch and reduced background K+ channel activity in cell-attached patch recordings. It is concluded that H2S excites type 1 cells through the inhibition of background (TASK) potassium channels leading to membrane depolarisation and voltage-gated Ca2+ entry. These effects mimic those of hypoxia. H2S also inhibited mitochondrial function over a similar concentration range as assessed by NADH autofluorescence and measurement of intracellular magnesium (an index of decline in MgATP). Cyanide inhibited background K channels to a similar extent to H2S and prevented H2S exerting any further influence over channel activity. These data indicate that the effects of H2S on background K channels are a consequence of inhibition of oxidative phosphorylation. Whilst this does not preclude a role for endogenous H2S in oxygen sensing via the inhibition of cytochrome oxidase, the levels of H2S required raise questions as to the viability of such a mechanism.
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