Functional mitochondria are required for O2 but not CO2 sensing in immortalized adrenomedullary chromaffin cells.
Am J Physiol Cell Physiol
; 294(4): C945-56, 2008 Apr.
Article
en En
| MEDLINE
| ID: mdl-18234847
ABSTRACT
Catecholamine (CAT) release from adrenomedullary chromaffin cells (AMC) in response to stressors such as low O(2) (hypoxia) and elevated CO(2)/H(+) is critical during adaptation of the newborn to extrauterine life. Using a surrogate model based on a v-myc immortalized adrenal chromaffin cell line (i.e., MAH cells), combined with genetic perturbation of mitochondrial function, we tested the hypothesis that functional mitochondria are required for O(2) sensing. Wild-type MAH cells responded to both hypoxia and increased CO(2) (hypercapnia) with K(+) current inhibition and membrane depolarization. Additionally, these stimuli caused a rise in cytosolic Ca(2+) and CAT secretion, determined by fura-2 spectrofluorimetry and carbon fiber amperometry, respectively. In contrast, mitochondria-deficient (rho(0)) MAH cells were hypoxia insensitive, although responses to hypercapnia and expression of several markers, including carbonic anhydrase II, remained intact. Rotenone (1 microM), a mitochondrial complex I blocker known to mimic and occlude the effects of hypoxia in primary AMC, was effective in wild-type but not rho(0) MAH cells. These data demonstrate that functional mitochondria are involved in hypoxia-sensing by adrenal chromaffin cells. We also show for the first time that, like their neonatal chromaffin cell counterparts, MAH cells are CO(2) sensors; however, this property is independent of functional mitochondria.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Oxígeno
/
Dióxido de Carbono
/
Médula Suprarrenal
/
Células Cromafines
/
Mitocondrias
Límite:
Animals
Idioma:
En
Revista:
Am J Physiol Cell Physiol
Asunto de la revista:
FISIOLOGIA
Año:
2008
Tipo del documento:
Article
País de afiliación:
Canadá