Effects of Norepinephrine on the Mechanoreceptors of the Urinary Bladder in the Cat / 대한마취과학회지

BACKGROUND: Recent findings suggest that a coupling between the somatic and sympathetic nervous system is critical not only for the development but also for the maintenance of pain behavioral changes. However, studies on the effect of sympathetic efferent system on sensory receptors in the visceral organ that is more dependent on the autonomic nervous system are lacking. This study examined whether norepinephrine (NE) had an influence on the mechanoreceptors in the feline urinary bladder. METHODS: Ten adult male cats were used and anesthetized with alpha-chloralose and artificially ventilated. A cannula with the pressure transducer was inserted through the urethra to apply mechanical stimuli and monitor the pressure of bladder. A tiny cannula inserted into the bilateral side branches of vesical arteries were used as a route for a NE (10A.M 9:40 01-10-08 bilaterally) injection. Nerve fiber recordings were obtained from the distal stump of the pelvic nerve. RESULTS: After the NE injection, the response of mechanoreceptors (n = 13) to the isotonic pressure stimulus (50 - 60 mmHg) decreased significantly (p < 0.05) in terms of sensitivity (i.e., ratio of nerve activity change to urinary bladder pressure change). The responses to pressure stimuli after an injection of an alpha1 adrenoceptor blocker (terazosin) reversed the effect of NE. The responses of mechanoreceptors to isotonic pressure stimulus were not affected significantly by NE with preinjection of an alpha2 adrenoceptor blocker (yohimbine). CONCLUSIONS: These results suggest that NE may have influence on the sensitivity of mechanoreceptors in the normal feline urinary bladder via an alpha1 adrenoceptor.

Effect of Clonidine on the Blood Pressure, Heart Rate and Plasma Catecholamine Concentration during General Anesthesia / 대한마취과학회지

BACKGROUND: Induction of general anesthesia with tracheal intubation and skin incision are potent stimuli that can induce increased sympathetic activity, heart rate and blood pressure. We compared the hemodynamic response and catecholamine concentration during general anesthesia with intravenous clonidine pretreatment, a centrally acting -2 adrenoceptor agonist, and without pretreatment. METHODS: Forty ASA I or II patients aged from 20 to 60 years undergoing elective surgery were randomly allocated to two groups. In group I, 5 ml of 0.9% normal saline as control administered intravenously 10 minutes before induction of anesthesia, and anesthesia was induced with thiopental sodium, succinylcholine and maintained with N2O (2.5L/min)-O2 (2.5L/min)-enflurane (1.3~1.8 vol%). In group II, 4 g/kg clonidine diluted in 5ml of normal saline administered intravenously 10 minutes before induction of anesthesia, and anesthesia was induced with thiopental sodium, succinylcholine and maintained with N2O-O2-enflurane (0.5~1.0vol%) and 2 g/kg/hr clonidine was continuously infused. We measured blood pressure, heart rate and plasma catecholamine at preinduction, 1 minute after intubation (T1), 1 (T2) and 30 minutes after skin incision (T3) and compared with group I. RESULTS: There was statistical significance in systolic and diastolic pressure at T1 between two groups. There was statistical significance in heart rate, epinephrine and norepinephrine at T1, T2 and T3 between two groups. CONCLUSION: The elevation of blood pressure, heart rate and plasma catecholamine accompanying tracheal intubation and skin incision may be prevented by administration of intravenous clonidine.

A Comparison of Serum Catecholamine Levels and Cardiovascular Responses during Anesthesia with Propofol or Enflurane / 대한마취과학회지

BACKGROUND: Surgical trauma is a potent stimulus for the neurohormonal axis. The catecholamine response to surgical stress may be modulated by the anesthetic regimen utilized. We compared the hemodynamic response and catecholamine concentration to lower abdominal surgery during anesthesia with propofol or enflurane. METHODS: Forty six patients undergoing lower abdominal surgery were assigned randomly to two groups. In group I, anesthesia was induced with thiopental sodium 5.0mg/kg and maintained with enflurane-N2O. In group II, anesthesia was induced with propofol 2.0mg/kg and maintained with propofol 12 mg/kg/min by infusion pump. Hemodynamic responeses were recorded at tracheal intubation. Blood samples for later determination of plasma catecholamine were drawn and hemodynamic responses were recorded at preinduction, 1 minute after skin incision, 30minutes after skin incision. RESULTS: There was no statistical significance in systolic and diastolic pressure between two groups. There was statistical significance in heart rate 30minutes after skin incision between two groups. There was no statistical significance in epineprine concentration between two groups. There was statistical significance in norepineprine 30 minutes after skin incision between two groups. CONCLUSIONS: Propofol may be useful alternative at lower abdominal surgery and it may be convenient and safe intravenous anesthetics.