Open AccessModulation of Recombinant Human T-Type Calcium Channels by Δ9-Tetrahydrocannabinolic Acid In Vitro
Author(s) -
Somayeh Mirlohi,
Chris Bladen,
Marina Santiago,
Mark Connor
Publication year - 2022
Publication title -
cannabis and cannabinoid research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.156
H-Index - 17
eISSN - 2578-5125
pISSN - 2378-8763
DOI - 10.1089/can.2020.0134
Subject(s) - voltage dependent calcium channel , chemistry , t type calcium channel , calcium channel , calcium , cannabinoid , patch clamp , biophysics , pharmacology , biochemistry , biology , receptor , organic chemistry
Low voltage-activated T-type calcium channels (T-type I Ca ), Ca V 3.1, Ca V 3.2, and Ca V 3.3, are opened by small depolarizations from the resting membrane potential in many cells and have been associated with neurological disorders, including absence epilepsy and pain. Δ 9 -tetrahydrocannabinol (THC) is the principal psychoactive compound in Cannabis and also directly modulates T-type I Ca ; however, there is no information about functional activity of most phytocannabinoids on T-type calcium channels, including Δ 9 -tetrahydrocannabinolic acid (THCA), the natural nonpsychoactive precursor of THC. The aim of this work was to characterize THCA effects on T-type calcium channels. Materials and Methods: We used HEK293 Flp-In-TREx cells stably expressing Ca V 3.1, 3.2, or 3.3. Whole-cell patch clamp recordings were made to investigate cannabinoid modulation of I Ca . Results: THCA and THC inhibited the peak current amplitude Ca V 3.1 with p EC 50 s of 6.0±0.7 and 5.6±0.4, respectively. THC (1 μM) or THC produced a significant negative shift in half activation and inactivation of Ca V 3.1, and both drugs prolonged Ca V 3.1 deactivation kinetics. THCA (10 μM) inhibited Ca V 3.2 by 53%±4%, and both THCA and THC produced a substantial negative shift in the voltage for half inactivation and modest negative shift in half activation of Ca V 3.2. THC prolonged the deactivation time of Ca V 3.2, while THCA did not. THCA inhibited the peak current of Ca V 3.3 by 43%±2% (10 μM) but did not notably affect Ca V 3.3 channel activation or inactivation; however, THC caused significant hyperpolarizing shift in Ca V 3.3 steady-state inactivation. Discussion: THCA modulated T-type I Ca currents in vitro , with significant modulation of kinetics and voltage dependence at low μM concentrations. This study suggests that THCA may have potential for therapeutic use in pain and epilepsy through T-type calcium channel modulation without the unwanted psychoactive effects associated with THC.