title: Catecholamine secretion by chemical hypoxia in guinea-pig, but not rat, adrenal medullary cells: differences in mitochondria.
abstract: The effects of mitochondrial inhibitors (CN(-), a complex IV inhibitor and CCCP, protonophore) on catecholamine (CA) secretion and mitochondrial function were explored functionally and biochemically in rat and guinea-pig adrenal chromaffin cells. Guinea-pig chromaffin cells conspicuously secreted CA in response to CN(-) or CCCP, but rat cells showed a little, if any, secretory response to either of them. The resting metabolic rates in rat adrenal medullae did not differ from those in guinea-pig adrenal medullae. On the other hand, the time course of depolarization of the mitochondrial membrane potential (ΔΨm) in guinea-pig chromaffin cells in response to CN(-) was slower than that in rat chromaffin cells, and this difference was abolished by oligomycin, an F1F0-ATPase inhibitor. The extent of CCCP-induced decrease in cellular ATP in guinea-pig chromaffin cells, which was indirectly measured using a Mg(2+) indicator, was smaller than that in rat chromaffin cells. Relative expression levels of F1F0-ATPase inhibitor factor in guinea-pig adrenal medullae were smaller than in rat adrenal medullae, and the opposite was true for F1F0-ATPase α subunit. The present results indicate that guinea-pig chromaffin cells secrete more CA in response to a mitochondrial inhibitor than rat chromaffin cells and this higher susceptibility in the former is accounted for by a larger extent of reversed operation of F1F0-ATPase with the consequent decrease in ATP under conditions where ΔΨm is depolarized.
authors.affiliation: Department of Cell and Systems Physiology, University of Occupational and Environmental Health, School of Medicine, Kitakyushu 807-8555, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Harada
authors.affiliation: Department of Cell and Systems Physiology, University of Occupational and Environmental Health, School of Medicine, Kitakyushu 807-8555, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Endo
authors.affiliation: Department of Cell and Systems Physiology, University of Occupational and Environmental Health, School of Medicine, Kitakyushu 807-8555, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Warashina
authors.affiliation: Department of Cell and Systems Physiology, University of Occupational and Environmental Health, School of Medicine, Kitakyushu 807-8555, Japan. Electronic address: minoue@med.uoeh-u.ac.jp.
authors.forename: M
authors.initials: M
authors.lastname: Inoue
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000313:Adrenal Medulla / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002395:Catecholamines / Q000378:metabolism*; D015687:Cell Hypoxia; D019439:Chromaffin Cells / Q000187:drug effects / Q000502:physiology*; D006168:Guinea Pigs; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology*; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D013045:Species Specificity
chemical_list: D002395:Catecholamines; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D000255:Adenosine Triphosphate
keywords: chemical hypoxia; chromaffin cell; mitochondria; oxidative phosphorylation; secretion