Selective pressure modulation of synaptic voltage-dependent calcium channels-involvement in HPNS mechanism.
Exposure to hyperbaric pressure (HP) exceeding 100 msw (1.1 MPa) is known to cause a constellation of motor and cognitive impairments named high-pressure neurological syndrome (HPNS), considered to be the result of synaptic transmission alteration. Long periods of repetitive HP exposure could be an occupational risk for professional deep-sea divers. Previous studies have indicated the modulation of presynaptic Ca(2+) currents based on synaptic activity modified by HP. We have recently demonstrated that currents in genetically identified cellular voltage-dependent Ca(2+) channels (VDCCs), CaV 1.2 and CaV 3.2 are selectively affected by HP. This work further elucidates the HPNS mechanism by examining HP effect on Ca(2+) currents in neuronal VDCCs, CaV 2.2 and CaV 2.1, which are prevalent in presynaptic terminals, expressed in Xenopus oocytes. HP augmented the CaV 2.2 current amplitude, much less so in a channel variation containing an additional modulatory subunit, and had almost no effect on the CaV 2.1 currents. HP differentially affected the channels' kinetics. It is, therefore, suggested that HPNS signs and symptoms arise, at least in part, from pressure modulation of various VDCCs.
Department of Physiology and Neurobiology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel. aviner@bgu.ac.il.
Ben
B
Aviner
Department of Physics, Jerusalem College of Technology, Jerusalem, Israel.
Gideon
G
Gradwohl
Department of Physiology and Neurobiology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.
Alice
A
Bliznyuk
Department of Physiology and Neurobiology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.
Yoram
Y
Grossman
D000818:Animals; D001464:Barium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism*; D005260:Female; D006610:High Pressure Neurological Syndrome / Q000378:metabolism*; D006801:Humans; D015640:Ion Channel Gating; D007700:Kinetics; D051379:Mice; D011312:Pressure; D011817:Rabbits; D051381:Rats; D013569:Synapses / Q000378:metabolism*; D013997:Time Factors; D014982:Xenopus laevis
D015220:Calcium Channels; D001464:Barium
high-pressure neurological syndrome; hyperbaric pressure; voltage-dependent calcium channel