Nitric oxide and potassium chloride-facilitated striatal dopamine efflux in vivo: role of calcium-dependent release mechanisms.
Previous studies investigating the calcium-dependency of nitric oxide-facilitated striatal dopamine efflux have produced conflicting results. In the current study, we have investigated the role of extracellular calcium in nitric oxide and potassium chloride-evoked striatal dopamine efflux in vivo using microdialysis. Dialysis probes were implanted in the anterior dorsal striatum of chloral hydrate-anesthetized rats. Intrastriatal infusion (20 min fraction) of the nitric oxide generators sodium nitroprusside (200 microM, 500 microM, or 1 mM) and 3-morpholinosydnonimine (1 mM) increased extracellular dopamine levels. The facilitatory effects of 3-morpholinosydnonimine and potassium chloride on dopamine efflux were attenuated following pretreatment (100 min) and co-infusion of calcium free artificial cerebral spinal fluid containing magnesium chloride. Local potassium chloride infusion (100 mM) administered alone elevated striatal dopamine efflux to a similar degree as potassium chloride (100 mM) delivered 60 min after 3-morpholinosydnonimine infusion. These results demonstrate that like potassium chloride, nitric oxide facilitates striatal dopamine efflux in vivo via a mechanism largely dependent on extracellular calcium. Also, as intrastriatal potassium chloride infusion evoked similar increases in extracellular dopamine levels in controls and subjects receiving pretreatment with the NO-generator 3-morpholinosydnonimine, it is unlikely that the functional integrity of DA nerve terminals is compromised via a neurotoxic disruption of plasma membrane potential following enhanced striatal NO production.
West
A R
AR
Department of Neuroscience, University of Pittsburgh, PA 15260, USA.
Galloway
M P
MP
D000818:Animals; D001692:Biological Transport; D003342:Corpus Striatum / Q000187:drug effects* / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D008297:Male; D008981:Molsidomine / Q000031:analogs & derivatives / Q000494:pharmacology; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D020030:Nitric Oxide Donors; D009599:Nitroprusside; D009569:Nitric Oxide; C002385:linsidomine; D011189:Potassium Chloride; D008981:Molsidomine; D004298:Dopamine