We examined the effects of α2-adrenergic agonist, dexmedetomidine(DEX), on tetrodotoxin-resistant (TTX-r) Na+ currents using small-sized dorsal root ganglion(DRG) cells of the rats. Whole cell patch-clamp configuration was used. After control Na+ current was recorded, DEX was added to the extracellular solution. Yohimbine and prazosin were used to differentiate the contribution of α2-adrenergic receptor from that of α1-adrenergic receptor. The peak TTX-r Na+ currents were significantly and dose dependently inhibited by DEX(p<0.05). Yohimbine attenuated the suppressive effects of DEX on TTX-r Na+ currents, while prazosin did not alter the effects of DEX. Thus, DEX inhibited TTX-r Na+ currents by way of α2-adrenergic receptors but not α1-adrenergic receptors. Therefore, it is suggested that DEX has an inhibitory effect on TTX-r Na+ channels through α2-adrenergic receptors.
We report successful anesthetic management of a patient with severe congestive heart failure(CHF). A 77-year-old male underwent total gastrectomy for the gastric cancer. He had been diagnosed of severe CHF like as dilated cardiomyopathy previously. The cardiac ultrasonography showed the enlarged left ventricle(LV) with LV diastolic internal dimension of 62mm and LV ejection fraction of 20%. Dopamine and colforsin daropate hydrochloride were administered to support cardiovascular performance. The cardiac index monitored by HemosonicTM was maintained over 3.0 liters/min/m2. The patient was weaned from the respirator 5 days after surgery and recovered to discharge by about 2 months.