| Effects of Intrathecal Calcium Channel Blockers on the MAC of Isoflurane in Rats. |
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Myung Ha Yoon, Jeong Il Choi, Seong Wook Jeong |
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Department of Anesthesiology and Pain Medicine, Medical School, Chonnam National University, Gwangju, Korea. mhyoon@chonnam.ac.kr |
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| Abstract |
BACKGROUND
Much evidence suggests that the spinal cord may be an important anesthetic action site. Volatile anesthetics have been shown to inhibit neurotransmitter release by inhibition of intracellular calcium entry. Many types of calcium channels (L, N, P, Q, T) were demonstrated in the dorsal horn of the spinal cord. Therefore, the aim of this study was to determine whether intrathecal calcium channel antagonists may change the minimum alveolar concentration (MAC) of isoflurane in rats and examine the role of spinal calcium channels for anesthetic action of isoflurane.
METHODS
In Sprague-Dawley rats, the MAC of isoflurane was determined by the tail-clamp technique. First, control MAC was determined and then changes of control MAC were observed after intrathecal administration of calcium channel antagonists. Change of mean arterial pressure (MAP) and general behavior were also examined following intrathecal delivery of calcium channel antagonists.
RESULTS
Neither abnormal behavior nor change of MAP occured after intrathecal injection of all types of calcium channel antagonists. All drugs decreased the MAC of isoflurane.
CONCLUSIONS
These results suggested that L, N, P, Q and T types of the calcium channel might play an important role in determining the MAC of isoflurane in the spinal cord. |
| Key Words:
Calcium channel; isoflurane; MAC; spinal cord |
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