The role of TASK-2 channels in CO2 sensing in zebrafish (Danio rerio).

The role of TASK-2 channels in CO2 sensing in zebrafish (Danio rerio). Am J Physiol Regul Integr Comp Physiol. 2020 Jul 22;: Authors: Koudrina N, Perry SF, Gilmour KM Abstract Peripheral chemosensitivity in fishes is thought to be mediated by serotonin-enriched neuroepithelial cells (NECs) that are localised to the gills of adults and the integument of larvae. In adult zebrafish (Danio rerio), branchial NECs are presumed to mediate the cardiorespiratory reflexes associated with hypoxia or hypercapnia whereas in larvae, there is indirect evidence linking cutaneous NECs to hypoxic hyperventilation and hypercapnic tachycardia. No study yet has examined the ventilatory response of larval zebrafish to hypercapnia and regardless of developmental stage, the signalling pathways involved in CO2 sensing remain unclear. In the mouse, a background potassium channel (TASK-2) contributes to the sensitivity of chemoreceptor cells to CO2. Zebrafish possess two TASK-2 channel paralogs, TASK-2 and TASK-2b encoded by kcnk5a and kcnk5b, respectively. The present study aimed to determine whether TASK-2 channels are expressed in NECs of larval zebrafish and whether they are involved in CO2 sensing. Using immunohistochemical approaches, TASK-2 protein was observed on the surface of NECs in larvae. Exposure of larvae to hypercapnia caused cardiac and breathing frequencies to increase, and these responses were blunted in fish experiencing TASK-2 and/or TASK-...
Source: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology - Category: Physiology Authors: Tags: Am J Physiol Regul Integr Comp Physiol Source Type: research