Transcript expression of inward rectifier potassium channels of Kir2 subfamily in Arctic marine and freshwater fish species

Abstract

Inward rectifier K + (Kir2) channels are critical for electrical excitability of cardiac myocytes. Here, we examine expression of Kir2 channels in the heart of three Gadiformes species, polar cod (Boreogadus saida) and navaga (Eleginus nawaga) of the Arctic Ocean and burbot (Lota lota) of the temperate lakes to find out the role of Kir2 channels in cardiac adaptation to cold. Five boreal freshwater species: brown trout (Salmo trutta fario), arctic char (Salvelinus alpinus), roach (Rutilus rutilus), perch (Perca fluviatilis) and pike (Esox lucius), and zebrafish (Danio rerio), were included for comparison. Transcript expression of genes encoding Kir2.1a, − 2.1b, − 2.2a, − 2.2b and − 2.4 was studied from atrium and ventricle of thermally acclimated or acclimatized fish by quantitative PCR. Kir2 composition in the polar cod was more diverse than in other species in that all Kir2 isoforms were relatively highly expressed. Kir2 composition of navaga and burbot differed from that of the polar cod as well as from those of other species. The relative expression of Kir2.2 transcripts, especially Kir2.2b, was higher in both atrium and ventricle of navaga and burbot (56-89% from the total Kir2 pool) than in other species (0.1-11%). Thermal acclimation induced only small changes in cardiac Kir2 transcript expression in Gadiformes species. However, Kir2.2b transcripts were upregulated in cold-acclimated navaga and burbot hearts. All in all, the cardiac Kir2 composition seems to be dependent on both phylogenetic position and thermal preference of the fish.

Indoxyl sulfate reduces Ito,f by activating ROS/MAPK and NF-κB signaling pathways

“…RNA isolation and qPCR. Total RNA isolation and qPCR were performed as previously described (69). Briefly, total RNA was extracted from NRVMs using TRIzol reagent (Invitrogen).…”

Ionic basis of atrioventricular conduction: ion channel expression and sarcolemmal ion currents of the atrioventricular canal of the rainbow trout (Oncorhynchus mykiss) heart

“…Here, we provide the first look at the ion channel diversity of AV nodal tissue of teleost heart. One characteristic of fish ion channels is the large number of gene paralogs which originates from the whole genome duplications in the teleost lineage (Jegla et al 2009;Glasauer and Neuhauss 2014;Hassinen et al 2019). The high diversity of ion channel genes provides raw material for adaptation to different environmental conditions (Glasauer and Neuhauss 2014).…”