M. Avella et al., Regulation of Cl- secretion in seawater fish (Dicentrarchus labrax) gill respiratory cells in primary culture, J PHYSL LON, 516(2), 1999, pp. 353-363
1. Primary cultures of sea bass (Dicentrarchus labrax) gill cells grown on
permeable membranes form a highly differentiated tight epithelium composed
of respiratory-like cells. This preparation was also found to provide a fun
ctional model for investigating the hormonal regulation of Cl- secretion.
2. In control conditions, i.e. in the absence of hormones or other stimuli,
the cultured epithelium showed a short-circuit current (I-sc) of 8.8 +/- 0
.4 mu A cm(-2), a transepithelial potential (V-t) of 28.6 +/- 0.6 mV (seros
al side positive), and a transepithelial resistance (R-t) of 5026 +/- 127 O
mega cm(2). Addition of 50 nM PGE(2) caused a stimulation of I-sc, V-t and
transepithelial conductance, G(t). The increase in I-sc was probably due to
the elevation in Cl- secretion, since it could be correlated with the stim
ulation of serosal to mucosal Cl-36(-) flux. Application of the neurohypoph
yseal peptide arginine vasotocin (AVT; 50 nM) or the beta-adrenergic agonis
t isoproterenol (isoprenaline; 0.5 mu M) evoked a stimulation in Cl- secret
ion, as was shown by the increases in I-sc and G(t). The excitatory effect
of isoproterenol followed by the inhibitory action of propranolol, a beta-a
drenergic antagonist, suggested the presence of beta-adrenergic receptors.
Noradrenaline (0.1 mu M) elicited a reduction in I-sc, V-t and G(t), which
was counterbalanced by the addition of phentolamine, an alpha-adrenergic an
tagonist. This suggested an activation of alpha-adrenergic receptors.
3. This study provides evidence for hormonal control of the Cl- secretion i
n sea bass gill respiratory cells in culture, involving AVT, prostaglandin
(PGE(2)), and beta- and alpha-adrenergic receptors.