Effects of pHi and pHe on membrane currents recorded with the perforated-patch method from cultured chemoreceptors of the rat carotid body.
In this study we investigated the effects of intracellular pH (pHi) and extracellular pH (pHe) on whole-cell currents in cultured glomus cells of the rat carotid body and small, intensely fluorescent (SIF) cells of sympathetic ganglia. The use of the perforated-patch recording technique along with established methods of cytoplasmic acidification allowed us to carry out this study without greatly disturbing the cell's endogenous pH regulatory mechanisms. A reversible decrease in the outward K+ current (20-30%) was observed during acid loading of glomus (and SIF cells) using the K+/H+ ionophore nigericin (3 microM) and acetate (20 mM). A reversible decrease in the inward Na+ current was also observed in both cell types during nigericin application. Application of amiloride (0.1 mM) to the bathing solution inhibited recovery of the K+ current from an acid load implicating the Na+/H+ antiporter as a mechanism involved in pH homeostasis in glomus cells. A reversible decrease in K+ and Na+ currents was also observed during changes in pHe from 7.4 to 6.5. The effects of pHi on membrane currents, Ca2+ levels, and neurotransmitter release are discussed in the context of the role of glomus cells as primary transducers of chemosensory stimuli in arterial blood.
Stea
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Department of Biology, McMaster University, Hamilton, Ont., Canada.
Alexander
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SA
Nurse
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CA
D000085:Acetates / Q000494:pharmacology; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D002344:Carotid Body / Q000502:physiology*; D002478:Cells, Cultured; D002628:Chemoreceptor Cells / Q000502:physiology*; D003035:Cobalt / Q000494:pharmacology; D003593:Cytoplasm / Q000502:physiology; D004594:Electrophysiology / Q000379:methods; D006863:Hydrogen-Ion Concentration; D008564:Membrane Potentials; D008959:Models, Neurological; D009550:Nigericin / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D051381:Rats
D000085:Acetates; D015221:Potassium Channels; D003035:Cobalt; D000584:Amiloride; D009550:Nigericin