Kir3.1 and Kir3.4 are abundant in the atrium and sinoatrial node of rats, guinea pigs, and ferrets, co-localizing with m2 muscarinic receptors, but have very low or undetectable abundance in the ventricle.
The functionally important effects on the heart of ACh released from vagal nerves are principally mediated by the muscarinic K+ channel. The aim of this study was to determine the abundance and cellular location of the muscarinic K+ channel subunits Kir3.1 and Kir3.4 in different regions of heart. Western blotting showed a very low abundance of Kir3.1 in rat ventricle, although Kir3.1 was undetectable in guinea pig and ferret ventricle. Although immunofluorescence on tissue sections showed no labeling of Kir3.1 in rat, guinea pig, and ferret ventricle and Kir3.4 in rat ventricle, immunofluorescence on single ventricular cells from rat showed labeling in t-tubules of both Kir3.1 and Kir3.4. Kir3.1 was abundant in the atrium of the three species, as shown by Western blotting and immunofluorescence, and Kir3.4 was abundant in the atrium of rat, as shown by immunofluorescence. Immunofluorescence showed Kir3.1 expression in SA node from the three species and Kir3.4 expression in the SA node from rat. The muscarinic K+ channel is activated by ACh via the m2 muscarinic receptor and, in atrium and SA node from ferret, Kir3.1 labeling was co-localized with m2 muscarinic receptor labeling throughout the outer cell membrane.
Dobrzynski et al. (Mon,) reported a other. Muscarinic K+ channel proteins Kir3.1 and Kir3.4 distribution was evaluated on Abundance and cellular location of Kir3.1 and Kir3.4. Kir3.1 and Kir3.4 are abundant in the atrium and sinoatrial node of rats, guinea pigs, and ferrets, co-localizing with m2 muscarinic receptors, but have very low or undetectable abundance in the ventricle.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: