Potassium evoked catecholamine release from the nucleus tractus solitarius in vitro.
The release of endogenous catecholamines (CA) from rat brain slices containing the nucleus tractus solitarius (NTS) was measured using a sensitive radioenzymatic assay. KCl (35 to 75 mM) induced a dose-related increase in norepinephrine (NE) release. Dopamine (DA) release was maximal with 50 mM KCl. An increase in epinephrine (E) release was only observed with 75 mM CKl. NE and E release was totally calcium-dependent whereas DA release was only partially calcium-dependent. Subsequent administrations of KCl released less CA. The calcium dependency of the KCl induced released of E, NE, and DA suggests a neurotransmitter function in the NTS for these CA. A difference in storage sites and/or mechanisms may be responsible for the observed differences in sensitivity to KCl and to extracellular calcium.
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism*; D004837:Epinephrine / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism*; D011189:Potassium Chloride / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains
D011189:Potassium Chloride; D002118:Calcium; D004298:Dopamine; D009638:Norepinephrine; D004837:Epinephrine