• Zhi-hua Sun, Qu-lian Guo, and Wang-yuan Zou.
• Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha 410008, China. sunzhihua-1@hotmail.com
• Zhong Nan Da Xue Xue Bao Yi Xue Ban. 2005 Feb 1;30(1):88-91.

ObjectiveTo observe the behaviour and Ca2+ content of spinal cord in rats after continuous spinal anesthesia administration of different densities and doses of ropivacaine in SD rats.MethodsTwenty-four male SD rats weighing 220 approximately 280 g were anesthetized. A polyurethane microspinal catheter was inserted into the lumbar subarachnoid space 8 cm according to the method of Yaksh's. The animals were randomly divided into 4 groups of 6 each: in group N the rats were given normal saline 40 microl intrathecally every one and half hours for 3 times; in group R1, 0.5% ropivacaine was given; in group R2 0.75% ropivacaine and in group R3 1% ropivacaine was given. The activity of rats was observed. After 6 hours rats were perfused with 4% formamint through the ascending aorta. The rats were sacrificed and L1 approximately 2 segment of spinal cord was immediately removed for Ca2+ content examination.ResultsA total hind limbs paralysis was seen at 30 seconds and intramuscular strain gradually came back from 30 to 90 minutes after the intrathecal administration of ropivacaine in all rats. The recovery of motor black was remarkably different in group R1, R2, and R3 (P < 0.05). The Ca2+ content of spinal cord was significantly higher in group R3 than that in group R1 and R2 (P < 0.05 ).ConclusionThere is no significant change of motor black time and it is related to drug dose for 0.5% , 0.75% and 1% ropivacaine in continuous spinal anesthesia. 1% ropivacaine may increase Ca2+ content in spinal cord.

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