Intracellular responses of rat hippocampal granule cells in vitro to discrete applications of norepinephrine.
In 75% of granule cells responsive to norepinephrine (NE), micropressure application of NE near the soma of intracellularly impaled granule cells produced membrane depolarizations. Depolarizations were associated with input resistance (Rin) increases; their amplitude increased with membrane depolarization; and had an equilibrium potential of -84 mV. The beta-adrenoceptor antagonist timolol blocked the depolarizations. In 38% of NE-sensitive granule cells, NE produced membrane hyperpolarizations. Hyperpolarizations were associated with decreases in Rin; increased with membrane depolarization; and reversed at greater than -99 mV. In some cells, in which NE was applied at different sites, both depolarizations and hyperpolarizations were observed. Both NE responses were observed in low Ca2+/high Mg2+ medium, suggesting they are due to direct postsynaptic actions of NE on granule cells.
Lacaille
J C
JC
Département de physiologie, Université de Montréal, Qué, Canada.
Schwartzkroin
P A
PA
D000818:Animals; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains
D009638:Norepinephrine