U73122

The following chemicals were products of R&D Systems: NT, TTX, kynurenic acid, picrotoxin, SR 48692, GDP-β-S, U73122, U73343, heparin, thapsigargin, chelerythrine, bisindolylmaleimide II (Bis II), ML 133, and tertiapin-Q (TQ). Dioctanoyl phosphatidylinositol 4,5-bisphosphate (dic8-PIP₂) was purchased from Echelon Biosciences. PD149163 was product of Millipore Sigma. Drugs were initially prepared in stock solution, aliquoted and stored at −20°C. For those chemicals requiring dimethyl sulfoxide (DMSO) as a solvent, the concentration of DMSO was less than 0.1%. This concentration of DMSO either in the recording pipettes or in the bath had no significant effects on NT-elicited facilitation of AP firing (data not shown).

The following chemicals were products of R&D Systems: AVP, TTX, kynurenic acid, picrotoxin, 6,7-dinitroquinoxaline-2,3-dione (DNQX), SR49059, GDP-β-S, U73122, U73343, heparin, thapsigargin, chelerythrine, bisindolylmaleimide II (Bis II), ML 133, ML 297, tertiapin-Q and tertiapin-LQ. Dioctanoyl phosphatidylinositol 4,5-bisphosphate (dic8-PIP₂) was purchased from Echelon Biosciences. Drugs were initially prepared in stock solution, aliquoted and stored at −20°C. For those chemicals requiring dimethyl sulfoxide (DMSO) as a solvent, the concentration of DMSO was less than 0.1%. This concentration of DMSO either in the recording pipettes or in the bath had no significant effects on neuronal activity.

Drugs and chemicals were dissolved in water or DMSO as stock solutions before being added to superfusate at 1:1000 dilutions. Control studies showed no effect of this DMSO concentration on membrane conductance or firing rate. Superfusate containing a chemical reached the recording chamber within 1 min after passing through a heat exchanger. The K-ATP channel opener Diazoxide was superfused for 5 min every 20 min; net Diazoxide-induced currents were measured as the difference between peak current and current immediately before application of Diazoxide. Test agents (dorsomorphin, STO-609, U73122, m-3M3FBS, m-CPP, and DHPG) were added to the superfusate 5 min after the first application of Diazoxide. The first application of Diazoxide was begun about 10 min after starting whole-cell recording. In some experiments dorsomorphin was added to the pipette internal solution and allowed to diffuse passively into the cell. Diazoxide was obtained from Sigma-Aldrich (St. Louis, MO, USA), m-CPP (meta- chlorphenylpiperazine) was from Tocris Cookson (Bristol, UK), dorsomorphin and STO-609 were from Cayman Chemical (Ann Arbor, MI, USA), U73122 and m-3M3FBS were from R&D Systems (Minneapolis, MN, USA), and DHPG ((S)-3,5-dihydroxyphenylglycine) was from Ascent Scientific (Cambridge, MA, USA).