The relaxant effect of clonidine and the possible involvement of imidazoline I1 receptors in bovine tracheal smooth muscle (BTSM) were examined. Clonidine caused concentration-dependent significant relaxation in BTSM precontracted with 0.1 or 1 microM carbachol (CCh) but not in 72.7 mM KCl-induced contraction. The relaxation in CCh-contracted BTSM was inhibited by yohimbine (1 microM) and idazo...

The effects of Hypericum perforatum (St John's wort) on morphine withdrawal syndrome and comparison with clonidine have been investigated in morphine-dependent rats. Adult male Wistar rats were subjects. The frequencies of withdrawal behavioral signs (rearing, teeth chattering and jumping) induced by naloxone challenge were demonstrated in morphine dependent rats receiving Hypericum perforatum ...

A single dose of clonidine developed tolerance to its analgesic effect. The tolerance reached its peak acutely on the 2nd day and lasted more than 5 days. Neither the analgesic effect nor the development of tolerance was modified by the pretreatment with naloxone. On the 2nd day, clonidine tolerant animals were also tolerant to morphine, but morphine tolerant animals, after a single dose of mor...

In order to assess the effect of spinal clonidine on tourniquet pain, 30 patients scheduled to undergo orthopaedic surgery under spinal anaesthesia were allocated randomly to two groups. Patients in group I (n = 15) received 0.5% isobaric bupivacaine 15 mg plus isotonic saline 1 ml. Patients in group II (n = 15) received 0.5% bupivacaine 15 mg plus clonidine 1 ml (150 micrograms). Sensory block...

Under controlled conditions, infant rats emit ultrasonic vocalizations during extreme cold exposure and after administration of the alpha(2) adrenoceptor agonist, clonidine. Previous investigations have determined that, in response to clonidine, ultrasound production increases through the 2nd-week postpartum and decreases thereafter. Given that sympathetic neural dominance exhibits a similar de...

Objectives. The aim of this study was to assess the effects of clonidine on intraoperative analgesia, sedation, intraocular and blood pressure, arrhythmia, and ischemia. Methods. Forty patients undergoing cataract surgery were allocated into two groups. They were monitored with Holter machine, the pupil was dilated, and 30 minutes later, 20 patients received clonidine (4 µg/kg), while the other...

INTRODUCTION Shivering, a common intraoperative problem under spinal anesthesia increases the oxygen consumption considerably and is uncomfortable and distressing to the patient, anesthesiologist as well as surgeon. The present study was designed to explore the effectiveness of tramadol, clonidine and dexmedetomidine in the treatment of post spinal anesthesia shivering and to look for their adv...

Objectives. To determine the sedative and respiratory effects of clonidine when used to evaluate growth hormone (GH) secretion in children with Prader Willi Syndrome (PWS). Methods. The study prospectively evaluated children with PWS who received clonidine (0.15 mg/m(2)) to assess GH responsiveness. Patients were studied up to four times over three years. Vital signs, oxygen saturation, and sed...

The delay τ between rising systolic blood pressure (SBP) and baroreflex bradycardia has been found to increase when vagal tone is low. The α(2)-agonist clonidine increases cardiac vagal tone, and this study tested how it affects τ. In eight conscious supine human volunteers clonidine (6 μg/kg po) reduced τ, assessed both by cross correlation baroreflex sensitivity and sequence methods (both P <...

Masuki, Shizue, Frank A. Dinenno, Michael J. Joyner, and John H. Eisenach. Selective 2-adrenergic properties of dexmedetomidine over clonidine in the human forearm. J Appl Physiol 99: 587–592, 2005. First published March 31, 2005; doi:10.1152/japplphysiol.00147.2005.— We tested the hypothesis that dexmedetomidine (Dex) has greater 2vs. 1 selectivity than clonidine and causes more 2-selective va...