• The Korean Journal of Pharmacology
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• v.25 no.1
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• pp.67-74
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• 1989

The effect of guanabenz on volume-induced micturition reflex contraction (VIMRC) in urethane-anethetized female rats was examined under adrenalectomy, chemical-sympathectomy, ganglionectomy, alpha-1, or alpha-2 blockade. Intracerbroventricular administration of guanalberz had little effect on VIMRC, but topical application suppressed amplitude and frequency of VIMRC. Guanabenz intravenous injection dose-dependently suppressed amplitude and frequency of VIMRC, with complete inhibition at dose of $100\;{\mu}g/kg$, but phenylephrine had no effect on VIMRC. Intravesicular peak pressure and amplitude of VIMRC were increased by 6-hydroxydopamine (6-OHDA) treatment when compared with control value, but yohimbine-, prazosin-hexamethonium-treatment and adrenalectomy did not show changes in VIMRC. Dose-response curve of guanabenz on amplitude and frequency of VIMRC shifted significantly to the right by treatment of yohimbine and 6-OHDA, and adrenalectomy. Median inhibitory dose $({\mu}g/kg)$ of guanabenz to amplitude of VIMRC showed 27.3 in control group, 381.6 in yohimbine, 294.1 in 6-OHDA and 54.1 in hexamethonium, and 38.8 in prazosin. Those of guanabenz to frequency of VIMRC showed 41.7 in control group, 571.1 in yohimbine, 410.8 in 6-OHDA, 141.4 in adrenalectomy, 59.6 in hexamethoinum and 31.4 in prazosin. These results suggest that guanabenz inhibits VIMRC through alpha-2 receptor stimulation rather than alpha-1 receptor stimulation and that catecholiamines released from sympathetic nerve ending and adrenal gland play a role in the inhibition.

• The Korean Journal of Pain
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• v.2 no.1
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• pp.66-71
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• 1989

It has been standard practice in many institutions to use a combination of a light general anesthesia and an epidural block for lower abdominal and pelvic surgery. This combination of a balanced anesthesia can provide various benefits to the patient such as less bleeding in the surgical field, the use of a lower concentration of general anesthetics, less muscle relaxant, and post operative pain management. However, there are several problems associated with hemodynamics such as bradycardia and hypotension etc. In order to block the pain of the high surgical area with a lumbar epidural puncture postoperatively, a large volume of local anesthetic is required and consequently an extensive blockade of sympathetic, sensory and motor functions can occur causing motor weakness, numbness and postural hypotension. Therefore, the patient is unable to have early ambulation postoperatively. In this study, thoracic epidural catheterization was undertaken to locate the tip of the catheter exactly at the surgical level for upper abdominal surgery, and was followed by general anesthesia. Twenty-one patients scheduled for upper abdominal surgery were selected. Fifteen of them had hepatobiliary operations and the remaining 6 had gastrectomies. Thoracic epidural punctures were performed mostly at T9-T10 (57.1%) and T8-T9. Neuromuscular blocking agents were not used in half of the cases and the, mean doses of relaxant were $3.5{\pm}1.0mg$ in gastrectomies, and $2.7{\pm}0.9mg$ in cases of hepatobiliary operation. Epidural morphine was injected 1 hour before the end of the operation for postoperative pain control. Eight patients did not require additional analgesics and the mean dose of epidural morphine was $2.2{\pm}0.9mg$, and 13 cases were given 0.125% epidural bupivacaine when patients complained of pain. Their initial doses of epidural morphine were $1.9{\pm}0.4mg$ and the mean duration of bupivacaine was 6 hours 20 minutes${\pm}40$ minutes. In conclusion. thoracic epidural analgesia is valuable to reduce postoperative pain in patients with upper abdominal surgery, However, it is not easy to maintain this balanced anesthesia with high epidural analgesia-and light general anesthesia for upper abdominal surgery because of marked hemodynamic changes. Therefore, further practice will be required.