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Effects of exogenous hydrogen sulphide on calcium signalling, background (TASK) K channel activity and mitochondrial function in chemoreceptor cells.
- Source :
-
Pflügers Archiv: European Journal of Physiology . May2012, Vol. 463 Issue 5, p743-754. 12p. 7 Graphs. - Publication Year :
- 2012
-
Abstract
- It has been proposed that endogenous HS mediates oxygen sensing in chemoreceptors; this study investigates the mechanisms by which HS excites carotid body type 1 cells. HS caused a rapid reversible increase in intracellular calcium with EC ≈ 6 μM. This [Ca] response was abolished in Ca-free Tyrode. In perforated patch current clamp recordings, HS depolarised type 1 cells from −59 to −35 mV; this was accompanied by a robust increase in [Ca]. Voltage clamping at the resting membrane potential abolished the HS-induced rise in [Ca]. HS inhibited background K current in whole cell perforated patch and reduced background K channel activity in cell-attached patch recordings. It is concluded that HS excites type 1 cells through the inhibition of background (TASK) potassium channels leading to membrane depolarisation and voltage-gated Ca entry. These effects mimic those of hypoxia. HS 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 HS and prevented HS exerting any further influence over channel activity. These data indicate that the effects of HS on background K channels are a consequence of inhibition of oxidative phosphorylation. Whilst this does not preclude a role for endogenous HS in oxygen sensing via the inhibition of cytochrome oxidase, the levels of HS required raise questions as to the viability of such a mechanism. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00316768
- Volume :
- 463
- Issue :
- 5
- Database :
- Academic Search Index
- Journal :
- Pflügers Archiv: European Journal of Physiology
- Publication Type :
- Academic Journal
- Accession number :
- 74130398
- Full Text :
- https://doi.org/10.1007/s00424-012-1089-8