PDE6B and retinitis pigmentosa 1: Since Frasson et al. [35] first reported the effects of D-cis-diltiazem, a benzothiazepin calcium channel antagonist which blocks both CNGC and VGCC, on photoreceptor protection in rd1 mice, several investigators have reported positive and negative effects of calcium channel blockers on animal models of RP [19–21, 36–43].