Glycine induces two distinct membrane currents in neonatal rat sympathetic preganglionic neurones in vitro.
1. The effects of glycine (Gly) on neonatal (12- to 16-day-old) rat sympathetic preganglionic neurones (SPNs) in transverse (500 microns) thoracolumbar spinal cord slices were studied by whole-cell patch-clamp techniques. 2. Gly elicited three types of membrane currents when applied to SPNs by pressure ejection (100 mM; 20-180 ms pulse duration): (1) an outward current (20/94 cells); (2) an inward current (30/94); and (3) a biphasic response (44/94) consisting of an outward followed by an inward current. 3. The Gly-induced outward current (IGly,(out)) had a mean reversal potential of -67 mV, was reversed in a low (5.7 mM) chloride Krebs solution, and was reversibly eliminated by strychnine (0.1-1 microM). 4. The Gly-induced inward current (IGly,(in)) had a mean reversal potential of -41 mV, was reduced in a Na(+)-free and increased in a high (15 mM) K+ solution; strychnine at the high concentration of 1 microM reduced the response by an average of 53%. 5. The electrophysiological and pharmacological characteristics of the biphasic response suggest that it was a combined response of outward and inward currents. 6. The results show that Gly elicits two distinct membrane currents, a Cl(-)-dependent outward current and a cationic inward current, which are mediated by strychnine-sensitive and strychnine-resistant Gly receptors. Functionally, activation of both types of Gly receptors reduces neuronal excitability and attenuates synaptic transmission.
Wu
S Y
SY
Department of Anatomy, Medical College of Ohio, Toledo 43614, USA.
Miyazaki
T
T
Dun
N J
NJ
D000320:Adrenergic Fibers / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D001339:Autonomic Fibers, Preganglionic / Q000166:cytology*; D002712:Chlorides / Q000378:metabolism; D004594:Electrophysiology; D005998:Glycine / Q000502:physiology*; D007473:Ion Channels / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D011188:Potassium / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012680:Sensitivity and Specificity; D013331:Strychnine / Q000494:pharmacology
D002712:Chlorides; D007473:Ion Channels; D013331:Strychnine; D011188:Potassium; D005998:Glycine