Jd. Kristensen et al., SPINAL-CORD BLOOD-FLOW AFTER INTRATHECAL INJECTION OF A N-METHYL-D-ASPARTATE RECEPTOR ANTAGONIST OR AN ADENOSINE RECEPTOR AGONIST IN RATS, Anesthesia and analgesia, 76(6), 1993, pp. 1279-1283
Evaluation of spinal cord blood flow (SCBF) is important as a preclini
cal screening for potential neurotoxicologic side effects before intro
ducing new therapeutic drugs for intrathecal (IT) administration. This
study was undertaken to determine whether two drugs with possible ant
inociceptive effects, the N-methyl-D-aspartate receptor antagonist 3-(
2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP) and the adenosi
ne agonist R-phenylisopropyladenosine (R-PIA), would affect SCBF after
IT administration in the rat. SCBF was measured 30 min after IT injec
tion of either saline, 4 nmol of CPP or 10 nmol of R-PIA in anesthetiz
ed rats by quantitative autoradiography with [C-14]iodantipyrine as a
tracer. No differences in SCBF were found between groups treated with
saline or CPP. In the group where R-PIA was administered IT, grey matt
er blood flow was 10% greater than in the group that received saline,
whereas no differences were found in white matter blood flow or in the
grey/white matter ratio between the groups. We concluded that neither
CPP nor R-PIA, when administered IT to anesthetized rats in provocati
ve doses within the upper pharmacologic dose range, reduces SCBF in ra
ts 30 min after IT injection. This indicates that neither neurotoxicol
ogic nor antinociceptive effects are likely to occur due to decrease i
n SCBE Our results do not indicate that these drugs should be avoided
for the treatment of pain.