AVT and IT regulate ion transport across the opercular epithelium of killifish (Fundulus heteroclitus) and gilthead sea bream (Sparus aurata)

作者：Antonio Martos Sitcha Juan; MartinezRodriguez Gonzalo; Miguel Mancera Juan; Fuentes Juan^*

来源：Comparative Biochemistry and Physiology A-Molecular & Integrative Physiology, 2015, 182: 93-101.

DOI：10.1016/j.cbpa.2014.12.027

• Fundulus heteroclitus
• Ion transport
• Isotocin
• Operculum
• Sparus aurata
• Vasotocin

The regulatory role of arginine vasotocin (AVT) and isotocin (IT) in Cl- secretion was investigated with the short circuit current (Isc) technique in opercular epithelia of killifish (Fundulus heteroclitus) and gilthead sea bream (Sparus aurata). Sea bream operculum showed similar to 4-fold lower number of Na/K-ATPase immunoreactive cells and similar to 12-fold lower secretory current than the killifish. In sea bream opercular membranes, the basolateral addition of AVT (10(-6) M) significantly stimulated Cl- secretion, while IT (10(-6) M) was without effect. In killifish, IT produced an immediate dose-dependent stimulation of Cl- secretion with significant effect at doses >= 10(-7) M and stimulation maxima (Delta Isc similar to 25 mu A.cm(-2)) at 10(-6) M. The basolateral addition of bumetanide (200 mu M) abolished >75% of the effect of IT on Cl- secretion. In turn, AVT had a dual effect on killifish opercular Isc: an immediate response (similar to 3 min) with Isc reduction in an inverted bell-shaped dose-response manner with higher current decrease (-22 mu A.cm(-2)) at 10(-8) M AVT, and a sustained dose-dependent stimulation of Cl- secretion (stable up to 1 h), with a threshold significant effect at 10(-8) M and maximal stimulation (similar to 20 mu A.cm(-2)) at 10(-6) M. Both effects of AVT appear receptor type specific. The VI-receptor antagonist SR 49059 abolished Isc reduction in response to AVT, while the specific V2-receptor antagonist (Tolvaptan, 1 mu M) abolished the stimulatory action of AVT on Cl- secretion. According to these results, we propose a modulatory role for AVT and IT in Cl- (NaCl) secretion across the opercular epithelium of marine teleost.

• 出版日期2015-4