Fig. 5.

TRPM4 is more abundant in rat Purkinje fibres than myocardium and a TRPM4 blocker attenuates stretch-induced ectopics

A. Purkinje Fibres (PF) and myocardium (M) were excised from the same area of rat LV free wall. (A) Tissue was immunolabelled for TRPM4 with primary antibody rabbit anti-TRPM4 (1:100; PA5-77324, Invitrogen) and secondary antibody goat anti-rabbit (1:200, Alexa 594. Thermofisher Scientific). Tissue was mounted in Prolong Gold (Thermofisher Scientific) on a glass slide. Two-dimensional images were acquired using an FV1000 Olympus confocal microscope. Increased TRPM4 immunofluorescence was observed in PF compared to M. Scale bar 250 μm. B. The integrated density and mean gray value of TRPM4 label was measured from myocardium and PFs (n = 3 hearts) using Image J-(Fiji) and presented as the mean integrated density ± SEM. Statistical analysis of data was performed in GraphPad Prism 7.03, and differences were compared using paired t-tests. The bar above the columns indicates (P < 0.05). C. Number of ectopics and period of ectopics for individual stretches under Tyrode to 50 μM 9-Phenanthrol (9-Phen) conditions in intact Langendorff hearts. 9-Phen (a TRPM4 blocker) caused a significant reduction in the number of ectopics. Data from 8 hearts and 15 stretches.Bars indicate P < 0.05. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)