In vivo uptake of [3H]nimodipine into brain during cortical spreading depression.
We report autoradiographic measurements of the in vivo uptake of [3H]nimodipine during the nonischemic depolarization of cortical spreading depression (CSD) in rat brain. [3H]Nimodipine uptake in brain was determined regionally in rats undergoing CSD (n = 8) and was significantly increased in cortex (14 +/- 7%) and hippocampus (10 +/- 6%) on the stimulated side relative to the contralateral hemisphere when compared with the same measurements in a control group (n = 8). A similar measurement using the physiologically inert radiotracer [14C]iodoantipyrine to control for potential effects of CSD on radioligand distribution showed a minimal increase (2.4 +/- 0.7%) of radiotracer uptake in cortex after CSD. This increase was significantly less than that observed in the [3H]nimodipine uptake studies. We hypothesize that increased in vivo [3H]nimodipine uptake in CSD identifies regions of depolarization and thus infers activation of the L-type voltage sensitive calcium channels.
Osuga
S
S
Neuroscience Research Institute, University of Ottawa, Canada.
Hakim
A M
AM
Osuga
H
H
Hogan
M J
MJ
D000818:Animals; D001345:Autoradiography; D002121:Calcium Channel Blockers / Q000008:administration & dosage / Q000494:pharmacology*; D015220:Calcium Channels / Q000502:physiology; D002540:Cerebral Cortex / Q000502:physiology; D013181:Cortical Spreading Depression / Q000187:drug effects / Q000502:physiology*; D006624:Hippocampus / Q000502:physiology; D008297:Male; D009553:Nimodipine / Q000008:administration & dosage / Q000493:pharmacokinetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014018:Tissue Distribution
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D009553:Nimodipine