L-type calcium channels (LTCCs; Cav1.1 - Cav1.4) belong to the family of voltage-gated calcium channels and are characterized by high voltage activation, sensitivity to dihydropyridines, long-lasting currents and slow inactivation kinetics.
It is proposed that calcium channel blockers (i.e. dihydropyridines and diltiazem) could have a beneficial effect for the rescue of photoreceptors in retinitis pigmentosa, a degenerative disease that can eventually lead to blindness. However, the isoform responsible remains unknown and further investigation is needed.
To further elucidate the electrophysiological and pharmacological characteristics of Cav1.3 and Cav1.4 a comparative study between these two subtypes was made using either a standard patch-clamp set-up or the semi-automated port-a-patch. Furthermore, a cell line stably expressing Cav1.4 was generated and the gating kinetics were compared with transiently transfected cells and a split-intein model (generated by Thomas Heigl, BSc.), which enables viral transfection by overcoming the packaging limitation.
The electrophysiological properties of the newly generated cell line stably expressing Cav1.4 were comparable to the control (transiently transfected tsA-201 cells) and in addition, the split-intein model of Cav1.4 showed no differences to control in the voltage-dependent parameters, therefore, reconstitution of a functional channel was successful.
The generation of these cell lines will hopefully further aid in elucidating the contribution of the respective isoforms to the beneficial effect found in retinitis pigmentosa pharmacological investigation studies.