Identification of RNA reads encoding different channels in isolated rat ventricular myocytes and the effect of cell stretching on L-type Cacurrent.

Background: The study aimed to identify transcripts of specific ion channels in rat ventricular cardiomyocytes and determine their potential role in the regulation of ionic currents in response to mechanical stimulation. The gene expression levels of various ion channels in freshly isolated rat ventricular cardiomyocytes were investigated using the RNA-seq technique. We also measured changes in current through Ca1.2 channels under cell stretching using the whole-cell patch-clamp method.

Results: Among channels that showed mechanosensitivity, significant amounts of TRPM7, TRPC1, and TRPM4 transcripts were found. We suppose that the recorded L-type Ca current is probably expressed through Ca1.2. Furthermore, stretching cells by 6, 8, and 10 μm, which increases I through the TRPM7, TRPC1, and TRPM4 channels, also decreased I through the Ca1.2 channels in K /K , Cs /K , K /Cs , and Cs /Cs  solutions. The application of a nonspecific I blocker, Gd, during cell stretching eliminated I through nonselective cation channels and I through Ca1.2 channels. Since the response to Gd was maintained in Cs /Cs  solutions, we suggest that voltage-gated Ca1.2 channels in the ventricular myocytes of adult rats also exhibit mechanosensitive properties.

Conclusions: Our findings suggest that TRPM7, TRPC1, and TRPM4 channels represent stretch-activated nonselective cation channels in rat ventricular myocytes. Probably the Ca1.2 channels in these cells exhibit mechanosensitive properties. Our results provide insight into the molecular mechanisms underlying stretch-induced responses in rat ventricular myocytes, which may have implications for understanding cardiac physiology and pathophysiology.