Effects of halothane anaesthesia and surgery on human growth hormone and insulin levels in plasma

Glucose use in fasted rats under sevoflurane anesthesia and propofol anesthesia

BACKGROUND

We previously reported the marked differences in the effects of sevoflurane anesthesia and propofol anesthesia on glucose use in fed rats; however, we could not elucidate mechanisms underlying the differences.

METHODS

We used fasted rats in this study. After surgical preparation under sevoflurane anesthesia, rats were divided into 3 groups: awake rats, rats under sevoflurane anesthesia, and rats under propofol anesthesia. All rats underwent the IV glucose tolerance test (IVGTT); 0.5 g/kg glucose was administered IV to rats. Just before IVGTT, some rats were pretreated with glibenclamide or diazoxide. We measured glucose, insulin, tumor necrosis factor-α (TNF-α), and high molecular weight adiponectin levels during IVGTT and calculated the quantitative insulin sensitivity check index (QUICKI) using glucose and insulin levels before glucose administration in each rat.

RESULTS

Before glucose administration, rats under sevoflurane anesthesia showed similar glucose and insulin levels with significantly higher QUICKI compared with awake rats, while rats under propofol anesthesia showed similar glucose levels and significantly higher insulin levels with significantly lower QUICKI compared with awake rats. After glucose administration, rats under sevoflurane anesthesia showed significantly higher glucose levels and similar insulin levels compared with awake rats, while rats under propofol anesthesia showed similar glucose levels and significantly higher insulin levels compared with awake rats. Before glucose administration, TNF-α levels in rats under sevoflurane anesthesia and rats under propofol anesthesia were similar to those in awake rats. After glucose administration, TNF-α was undetectable in all awake rats and all rats under sevoflurane anesthesia, whereas TNF-α was detectable in all rats under propofol anesthesia; TNF-α levels in rats under propofol anesthesia were significantly higher than those in awake rats. High molecular weight adiponectin levels in rats under sevoflurane anesthesia and rats under propofol anesthesia were similar to those in awake rats throughout the experimental period. In rats under sevoflurane anesthesia, glibenclamide significantly decreased glucose levels and significantly increased insulin levels; however, diazoxide produced no significant effects on glucose and insulin levels. In rats under propofol anesthesia, glibenclamide significantly decreased glucose levels and significantly increased insulin levels, while diazoxide significantly decreased glucose levels without changing insulin levels.

CONCLUSIONS

Sevoflurane anesthesia attenuates glucose-induced insulin secretion without affecting basic insulin secretion, while propofol anesthesia enhances insulin secretion. Propofol anesthesia exaggerates insulin-resistive conditions, whereas sevoflurane anesthesia dose not impair insulin sensitivity; there may be a possible association of TNF-α with insulin-resistive conditions under propofol anesthesia.

The involvement of adenosine triphosphate-sensitive potassium channels in the different effects of sevoflurane and propofol on glucose metabolism in fed rats

BACKGROUND

Recently, we reported marked differences in the effects of sevoflurane and propofol on glucose metabolism; glucose use is impaired by sevoflurane, but not by propofol. Opening of adenosine triphosphate-sensitive potassium channels (K(ATP) channels) in β islet cells attenuates insulin secretion, while inhibition of K(ATP) channels in β islet cells increases insulin secretion. It is reported that volatile anesthetics open K(ATP) channels, whereas propofol inhibits K(ATP) channels. In this study, we examined the effects of sevoflurane and propofol on glucose metabolism under normovolemic and hypovolemic conditions, focusing on insulin secretion.

METHODS

Anesthesia was induced with sevoflurane (3% in 1 L/min oxygen) in all rats. After surgical preparation, rats were assigned to 2 groups. Anesthesia was maintained with sevoflurane (2% in 1 L/min oxygen) in the 1st group, and with propofol (a bolus dose of 30 mg/kg followed by continuous infusion at a rate of 30 mg · kg(-1) · h(-1)) in the 2nd group. Each group was divided into 3 subgroups: rats without pretreatment, rats pretreated with glibenclamide, and rats pretreated with nicorandil. After a 30-minute stabilization period, we withdrew 15 mL/kg of blood to induce hypovolemia. We evaluated glucose metabolism under both normovolemic and hypovolemic conditions by measuring blood glucose levels and plasma insulin levels.

RESULTS

Under both normovolemia and hypovolemia, glucose levels in rats anesthetized with sevoflurane were significantly higher than those in rats anesthetized with propofol, and insulin levels in rats anesthetized with sevoflurane were significantly lower than those in rats anesthetized with propofol. Glibenclamide, a K(ATP) channel inhibitor, significantly decreased glucose levels and significantly increased insulin levels under sevoflurane anesthesia, suggesting that sevoflurane decreases insulin secretion by opening K(ATP) channels in β islet cells. Glibenclamide significantly decreased glucose levels and significantly increased insulin levels under propofol anesthesia as well; however, insulin levels in rats pretreated with glibenclamide under propofol anesthesia were much higher than those in rats pretreated with glibenclamide under sevoflurane anesthesia. Furthermore, insulin levels in rats without pretreatment under propofol anesthesia seemed to be equal to or higher than those in rats pretreated with glibenclamide under sevoflurane anesthesia. These results suggest that there are marked differences in the effects of sevoflurane and propofol on insulin secretion regulated by K(ATP) channels in β islet cells. Nicorandil, a K(ATP) channel opener, produced no significant effects on glucose metabolism under both sevoflurane and propofol anesthesia.

CONCLUSIONS

Insulin secretion regulated by K(ATP) channels in β islet cells is involved, at least in part, in the different effects of sevoflurane and propofol on glucose metabolism.

Halothane and sevoflurane decrease norepinephrine-stimulated glucose transport in neonatal cardiomyocyte

Catecholamine regulates myocardial glucose use. However, the effect of inhaled anesthetics on myocardial glucose transport stimulated by catecholamine is unclear. We studied the effect of halothane and sevoflurane on uptake of 2-deoxyglucose stimulated by norepinephrine in neonatal cardiomyocytes and the mechanism that modulates glucose transport. We studied the effects of halothane and sevoflurane on norepinephrine (NE)-stimulated glucose uptake and the effects of halothane and sevoflurane on glucose uptake stimulated by W7 (a calcium releasing agent), phorbol 12 myristate-13-acetate (a protein kinase C agonist), and LiCl. Sevoflurane decreased NE-stimulated glucose uptake from 63.7 +/- 7.0 to 41.2 +/- 3.7 pmol h(-1) mg protein(-1), and halothane also attenuated NE-stimulated glucose uptake to 37.8 +/- 5.7 pmol h(-1) mg protein(-1). W7 at 10 micromol/L increased glucose uptake from 16.4 +/- 1.4 to 41.2 +/- 3. 4 pmol h(-1) mg protein(-1). The stimulation was inhibited in the presence of 0.8 mmol/L sevoflurane and 0.58 mmol/L halothane to 23.9 +/- 3.7 and 25.6 +/- 3.6 pmol h(-1) mg protein(-1), respectively. Halothane and sevoflurane did not significantly affect the glucose uptake stimulated by 1 nmol/L insulin, 10 micromol/L PMA, or 10 mmol/L LiCl. We conclude that halothane and sevoflurane decrease NE-stimulated glucose uptake through decrease in intracellular calcium in cardiomyocytes.

IMPLICATIONS

The effect of inhaled anesthetics on myocardial glucose uptake during administration of catecholamine is unclear. The myocardial glucose uptake is stimulated not only by catecholamine, but also by insulin, protein kinase C, and increase of intracellular calcium. We examined the effects of halothane and sevoflurane on glucose uptake.

The effects of feeding on the development of metabolic acidosis in the rat: Comparison between perfused liverin situ and whole animal

Rat liver perfused in situ was charged with two concentrations of halothane. Lactate increased in a time- and dose-dependent manner in the liver of the fed rat, whereas its increase in the starved rat was much milder (1.7 --> 9.2 mmol. l(-1) vs 0.6 --> 1.4 mmol. l(-1) after a 3 hr charge with 6.0% halothane). Base excess decreased also more markedly in the fed rat. Glucose increased 2.3 times the control value in the fed rat, whereas it did not change significantly in the starved rat. Changes produced by enflurane were very similar to those produced by halothane. It was inferred that in the presence of halothane and enflurane, hepatic glycogen was transformed into glucose and then to lactate by the inhibition of NADH dehydrogenase. In the liver of the starved rat, glucose, hence lactate, did not increase because of the depletion of glycogen. When halothane (1.9%) was given to the whole animal, changes in lactate, base excess and glucose in the arterial blood were very mild. Marked disparities in these parameters between the two experimental models were inferred to be due to: 1) possible insinuation of anaerobic metabolism in the perfusion experiments, 2) a well-kept balance between the suppression of cellular metabolic activity and inhibition of energy production by halothane in the whole animal, and 3) involvement of neural and humoral factors in the intact whole animal.

The effects of open heart surgery on growth hormone, cortisol and insulin levels in man. Hormone levels during open heart surgery

Plasma growth hormone, cortisol, insulin and blood glucose concentrations were measured intra- and postoperatively in ten patients who underwent open heart surgery with moderate hypothermia. Diazepam-ketamine anaesthesia for 10-20 min failed to precipitate any significant alterations in the levels of measured hormones and blood glucose. In the pre-bypass period of surgery, an increase in cortisol and a slight elevation in growth hormone levels was observed; insulin level showed no change in spite of marked hyperglycaemia. The bypass period, including hypothermia and haemodilution, was accompanied by unchanged cortisol and elevated growth hormone levels, while insulin demonstrated a slight rise which did not correspond with the degree of hyperglycaemia. The post-bypass period with rewarming the restoring spontaneous circulation was characterized by further marked increase in cortisol and growth hormone levels and, in spite of decreasing levels of blood glucose, by a paradoxical elevation in plasma insulin. It is suggested that hypothermia, haemodilution, reduced tissue perfusion affecting endocrine glands, as well as denaturation of some hormones in the oxygenator, participate in the moderate endocrine response, disproportionate to the stress of cardiopulmonary bypass surgery. The rise in hormone levels on terminating bypass seems to be dependent on the improved blood flow to endocrine glands due to recovered spontaneous circulation, rewarming and, as for insulin, presumably even on the reduced inhibitory effect of catecholamines.

Intravenous glucose tolerance test during anaesthesia in dogs: insulin response and glucose clearance

To evaluate the insulin response and the rates of disappearance of glucose from plasma during high spinal analgesia and various types of general anaesthesia, a series of intravenous glucose tolerance tests was performed in six dogs. Plasma glucose and insulin levels were measured during the intravenous glucose tolerance tests. Insulinogenic indices were calculated. The values obtained during anaesthesia were compared to those obtained during an unanaesthetized state. The insulinogenic index was increased significantly during high spinal analgesia and thiopentone infusion. Halothane and enflurane anaesthesia decreased the insulinogenic index significantly while Innovar-nitrous oxide also decreased it, but not significantly. These findings suggest that insulin secretion in response to hyperglycaemia is stimulated by spinal analgesia and thiopentone anaesthesia, depressed by halothane and enflurane anaesthesia and unchanged during neuroleptanesthesia. A diuresis was observed in the thiopentone anaesthetic and spinal analgesic groups as compared to the other general anaesthetic groups. Urinary losses of insulin and glucose paralleled urinary output; yet the greatest mean urinary loss of glucose did not exceed 4.5 per cent of the load of glucose administered. Accordingly, 95 per cent of the administered glucose remained within the body, presumably available for utilization.

Lipid metabolites and nitrogen balance after abdominal surgery in man

The relation of lipid metabolism to nitrogen balance was studied in patients having undergone abdominal surgery and was compared with control subjects who had fasted for a similar period. The patients had lower circulating concentrations of glycerol, non-esterified fatty acids and ketone bodies. There were inverse correlations between blood alanine and ketone body concentrations in both patients (r = -0.64, P less than 0.01) and controls (r = -0.58, P less than 0.01). Nitrogen excretion by patients (12.7 mmol/kg body weight/day +/- 1.4 s.e. mean) was greater than by controls (9.2 mmol kg(-1)d(-1) +/- 0.8, P less than 0.05), but a more marked difference was noted for urinary methyl histidine excretion of 5.1 +/- 0.5 mmumol kg(-1) d(-1) by patients and only 2.5 +/- 0.3 mumol kg(-1) d(-1) by controls (P less than 0.01), a disparity indicative of more active protein turnover after surgery.

Epidural analgesia improves postoperative nitrogen balance

Postoperative nitrogen balance was monitored in twelve patients undergoing hysterectomy under either epidural analgesia or general anaesthesia. The mean cumulative five-day nitrogen losses were significantly lower after epidural analgesia than after general anaesthesia. Nitrogen sparing presumably results from inhibiting the stress-induced release of catabolic hormones, since epidural analgesia abolished postoperative hyperglycaemia and increase in plasma cortisol concentrations. No adverse effects of inhibiting the stress response were observed. Neurogenic stimuli thus play a crucial part in the catabolic response to surgery. Inhibiting the endocrine metabolic response to trauma by neurogenic blockade may reduce the morbidity precipitated in high-risk patients by the catabolic response to surgery.

The influence of phentolamine, an adrenergic blocking agent, on insulin secretion during surgery

A rapid intravenous glucose load (20 g) was given with a phentolamine infusion during and after elective abdominal surgery. Plasma levels of glucose, free fatty acids, and insulin were measured to investigate the influence of surgical stress on insulin secretion. When Ringer's lactate solution was infused into a control group of subjects during surgery, plasma levels of insulin did not change during and after the surgery while plasma levels of glucose and free fatty acids increased gradually during this period. Similar results were also noted in another control group in whom only Ringer's lactate solution and phentolamine had been infused. This evidence suggests that insulin secretion responding to endogenous hyperglycemia is suppressed during surgery. In the group which was given the glucose load during infusion of only Ringer's lactate solution, plasma levels of insulin significantly increased soon after the glucose load and the gradually decreased. In another group which was given the glucose load during infusion of Ringer's lactate and phentolamine, plasma levels of insulin also increased significantly after the glucose load and remained elevated during surgery. The maximum increment of plasma insulin after the glucose load in the latter group was significantly higher than that in the former group. From these results it is suggested that suppression of insulin secretion by surgical stress is inhibited by the alpha blocking agent phentolamine.

Effect of anaesthesia and surgery on blood sugar and carbohydrate tolerance in African children

The effect of pre-operative starvation, anaesthesia and surgery on blood sugar levels and the handling of carbohydrate load during operation were studied in 28 Nigerian children between 2 months and 15 years of age. (1) Age and body weight were important factors influencing the relationship between duration of pre-operative fast and the pre-induction blood sugar level in children. Hypoglycaemic values occurred in 7 per cent of the subjects studied although none was clinically hypoglycaemic. (2) Halothane anaesthesia alone did not affect blood sugar levels but relaxant anaesthesia in this study caused significant rise of blood sugar. (3) There was a marked hyperglycaemic response to surgery and handling of glucose load during operation was significantly poorer than before operation.

Effects of halothane on the metabolism of human adipose tissue

The metabolism of specimens of human adipose tissue exposed to different concentrations of halothane was studied. Halothane was added to the incubation medium directly or via the gas phase above the medium. The basal lipolysis was significantly increased by low concentrations of halothane. Higher concentrations clearly diminished the lipolysis, but here, in spite of the inhibitory effect on the basal lipolysis, the lipolytic effect of noradrenaline expressed as percent increment was increased. The rate of lipid synthesis from glucose was reduced when halothane was present in the gas phase. The effect of insulin on glucose metabolism was not affected by the presence of halothane, while the antilipolytic action was abolished by high concentrations of halothane. The results show that halothane may exert dual effects on the mobilization of lipids from human adipose tissue; at low concentrations halothane enhances the basal lipolysis, while at higher concentrations it exerts inhibitory effects.

Effect of isoflurane anaesthesia and surgery on carbohydrate metabolism and plasma cortisol levels in man

The present study was undertaken to investigate in nine male surgical patients the effects of isoflurane anaesthesia alone on the carbohydrate metabolism by determining plasma growth hormone (GH), insulin, blood glucose, and cortisol, and to compare them with the effects of anaesthesia associated with surgical operations. Determination of plasma GH, insulin, cortisol, and blood glucose were made simultaneously before induction of isoflurane anaesthesia, after maintenance of anaesthesia for 15 minutes and 30 minutes and during and after conclusion of the operation. Plasma GH concentrations showed a significant elevation during isoflurane anaesthesia, and maintained a similar high level one hour after the start of the operation. An insignificant elevation in plasma insulin level and significant increases in blood glucose were noted during anaesthesia and operation. Plasma cortisol levels increased insignificantly during anaesthesia, but increased markedly during operation. Our observations would suggest that the increased blood level of GH and elevated blood cortisol play a part in the increase of blood glucose during isoflurane anaesthesia and surgical operations in man.

Glucose utilization and insulin secretion during surgery in man

Intravenous glucose tolerance tests were performed in 18 patients before, during and after surgery. Glucose utilization was found to be significantly depressed during and after operation to a degree which increased with the severity of operation. Suppression of insulin secretion was observed during operation together with increased plasma cortisol levels and an increased urinary catecholamine excretion. It is suggested that a failure of cellular glucose utilization is the primary event in the metabolic response to injury which initiates cellular catabolism and urinary nitrogen loss.