Different Ca2+ source for slow AHP in completely adapting and repetitive firing pyramidal neurons

• Published in: Neuroreport Vol. 10; no. 9; pp. 1951 - 1956
• Main Authors: Pineda, J C, Galarraga, E, Foehring, R C
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD Lippincott Williams & Wilkins, Inc 23-06-1999; Lippincott Williams and Wilkins
• Subjects: Action Potentials - drug effects; Action Potentials - physiology; Adaptation, Physiological; Animals; Biological and medical sciences; Calcium - physiology; Calcium Channel Blockers - pharmacology; Calcium Channels, L-Type - physiology; Calcium Channels, Q-Type - physiology; Central nervous system; Dantrolene - pharmacology; Electrophysiology; Female; Fundamental and applied biological sciences. Psychology; Male; Muscle Relaxants, Central - pharmacology; Neocortex - chemistry; Neocortex - cytology; Neocortex - growth & development; Nifedipine - pharmacology; omega-Agatoxin IVA - pharmacology; omega-Conotoxin GVIA - pharmacology; omega-Conotoxins; Organ Culture Techniques; Peptides - pharmacology; Pyramidal Cells - chemistry; Pyramidal Cells - physiology; Rats; Rats, Sprague-Dawley; Ryanodine - pharmacology; Stimulation, Chemical; Vertebrates: nervous system and sense organs; Cerebral cortex; Calcium; Rat; Rodentia; Central nervous system; Discharge pattern; Electrophysiology; Ionic channel; Vertebrata; Mammalia; Development; Pyramidal neuron; Hyperpolarization; Release; Brain (vertebrata)
• ISSN: 0959-4965; 1473-558X
• DOI: 10.1097/00001756-199906230-00029

INTRACELLULAR recordings in an in vitro neocortical slice preparation from immature rats were used to investigate the Ca source for slow afterhyperpolarization (sAHP) generation in pyramidal neurons that exhibit complete spike frequency adaptation (CA neurons). In pyramidal neurons that maintain repetitive firing for long periods of time (RF neurons), N-, P- and Q-type Ca channels supply Ca for sAHP generation. In CA neurons, the sAHP was reduced by only 50% by the combination of antagonists for these Ca channel types and L-type channels. Ryanodine and dantrolene, blockers of Ca −induced Ca release, reduced the sAHP by ∼45% in CA neurons, but caused no reduction of the sAHP in RF neurons. Dantrolene application caused CA neurons to fire throughout a 1 s suprathreshold current injection (as do RF neurons).