Synaptosomal respiration: a potent indicator of veratridine-induced Na influx.
Inhibition of the voltage-dependent Na channel by tetrodotoxin (5 mumol/l) decreased by about 86% the stimulation of the respiration of rat brain synaptosomes induced by veratridine (10 mumol/l). A similar effect was achieved by blocking Na(+)-K(+)-ATPase with ouabain (1 mmol/l). Pharmacological manipulations of Ca homeostasis suggested that the veratridine-induced stimulation of respiration did not depend upon Ca entry. These data suggest that the veratridine-induced stimulation of synaptosomal respiration may result primarily from an increase in intracellular Na+. They provide the basis for an indirect method, which only requires recording of synaptosomal respiration, to test drugs for their possible interaction with excessive Na influxes.
Urenjak
J
J
Department of Experimental Medicine, Janssen Research Foundation, Neuss, FRG.
Tegtmeier
F
F
Beile
A
A
Khan
S
S
Peters
T
T
D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D008297:Male; D010042:Ouabain / Q000494:pharmacology; D010101:Oxygen Consumption / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism*; D015222:Sodium Channels / Q000187:drug effects / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*; D014701:Veratridine / Q000494:pharmacology*
D002121:Calcium Channel Blockers; D015222:Sodium Channels; D010042:Ouabain; D014701:Veratridine; D000584:Amiloride; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium