Improvement in post-traumatic spinal cord blood flow with a combination of a calcium channel blocker and a vasopressor.
We have recently shown that nimodipine, a calcium channel blocker, can increase spinal cord blood flow (SCBF) in normal rats and can improve SCBF after spinal cord trauma if the mean systemic arterial pressure (mSAP) is restored to normal levels by the vasopressor, adrenalin. The present study is a further analysis of the improvement in post-traumatic SCBF (measured with the hydrogen clearance technique) with the combination of adrenalin and nimodipine. In addition, image analysis was used to study the potential risk of this combination for exacerbating intramedullary hemorrhage in the injured spinal cord. SCBF, mSAP, and other physiologic parameters were measured preinjury, postinjury, and post-treatment. A 53.0-gram clip compression injury at the T1 spinal segment was delivered for 1 minute to three treatment groups (saline, adrenalin, and adrenalin plus nimodipine) comprised of five rats each. Injury caused a marked decline in SCBF and mSAP. Treatment with adrenalin alone or combined with nimodipine (1.5 micrograms/kg/min IV) improved mSAP to 100-125 mm Hg. However, adrenalin alone failed to improve SCBF, whereas nimodipine plus adrenalin produced a marked improvement of approximately 60% in post-traumatic SCBF. Morphometric analysis showed no significant difference between per cent area or volume of hemorrhage between the three treatment groups, although there was a trend for increased hemorrhage in the adrenalin-alone group perhaps due to the higher post-traumatic mSAP in this group. Further studies are required to find the minimal elevation in mSAP produced by a vasopressor that would still cause an improvement in post-traumatic SCBF by nimodipine, and to determine whether this combination improves function after spinal cord injury.
Guha
A
A
Division of Neurosurgery, Toronto Western Hospital, University of Toronto, Ontario, Canada.
Tator
C H
CH
Smith
C R
CR
Piper
I
I
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D004359:Drug Therapy, Combination; D004837:Epinephrine / Q000627:therapeutic use; D006400:Hematocrit; D007511:Ischemia / Q000188:drug therapy*; D008297:Male; D009553:Nimodipine / Q000627:therapeutic use*; D051381:Rats; D011919:Rats, Inbred Strains; D013116:Spinal Cord / Q000098:blood supply*; D013119:Spinal Cord Injuries / Q000097:blood / Q000503:physiopathology*
D009553:Nimodipine; D004837:Epinephrine