A) Representative photomicrographs of SANcm selected for patching studies from CTRL (Ai) and cRadKO (Aii) hearts. B) Cell capacitance is not significantly different (p = 0.77). C) Family of ICa,L for CTRL (blue) and cRadKO (red). Scale bars: 5 pA/pF, 100 ms. D) Current-voltage relationships for peak ICa,L from CTRL and cRadKO SANcm. E) Maximal conductance is significantly increased (**p<0.01) and F) activation midpoint trends toward a negative shift with Rad deletion (p=0.2). N = 8 mice, n = 17 cells for CTRL; N = 9 mice, n = 21 cells for cRadKO.