Effects of inhibition of adrenal steroidogenesis on compensation of fluid loss and on survivial after limb ischaemia in the rat

The corticosteroid synthesis inhibitor metyrapone markedly enhances the behavioural effects of d-amphetamine

The clinically utilized corticosteroid synthesis inhibitor metyrapone attenuates the behavioural effects of cocaine in the rat. Given the potential therapeutic implications of this interaction, we felt it important to determine if metyrapone's action would generalize to another widely abused psychostimulant, namely d-amphetamine. However, rather than producing attenuation, metyrapone preadministration (3 x 100 mg/kg) markedly enhanced both the locomotor activating and stereotypy-inducing actions of d-amphetamine (dose equivalent to 2.5 mg/kg free base). The fact that the corticosteroid synthesis inhibitor trilostane did not affect the behavioural action of d-amphetamine suggests that inhibition of corticoid synthesis does not underlie the action of metyrapone. Instead, it is argued that inhibition of debrisoquine hydroxylase (cytochrome p450 2D1), an enzyme involved in the metabolism of d-amphetamine, represents the critical mechanism of action.

Cardiovascular instability following bolus dose of etomidate

A patient with alveolar proteinosis developed unexpected cardiovascular instability after broncho-alveolar lavage. He had received two bolus doses of etomidate within an 18-hour period. Serum cortisol concentrations were low and hydrocortisone replacement therapy was necessary to restore arterial pressure. Implications for management of critically ill patients who receive bolus doses of etomidate are discussed.

Interpretation of the metabolic effects of trauma and sepsis

John Hunter suggested that the body's responses to injury were defensive and had survival value. Now, many years later, we are still uncertain about this. Although our appreciation of the endocrine and metabolic responses to injury, both physical and bacterial, has increased enormously our knowledge of these events, particularly at a molecular level, is still very incomplete. Patterns have been identified, however, in the sphere of energy metabolism, and this provides a basis for interpreting at least some of the biochemical responses to injury. The views developed support the idea that the responses are defensive--initially against the impact of the injury and then to meet the demands of the new "organ" which the wounds or septic focus seem to have added to the body. A reason for wanting to interpret these responses is to improve patient care. Current interpretations at least help to clarify our view of what is happening in the injured or septic patient and sometimes indicate lines of treatment. Nevertheless, many serious problems, particularly changes in protein metabolism, remain to be solved before we can advise on the metabolic care of patients at all stages from accident to recovery.

The effects of stress and injury on the activity of phosphoenolpyruvate carboxykinase in the liver of the rat

The effects of stress (diethyl ether anaesthesia for 4-8 min, or intravenous injection of 0.05 ml of a dimethyl sulphoxide/water mixture) and of a scald injury given under ether anaesthesia on hepatic PEPCK (phosphoenolpyruvate carboxykinase, EC 4.1.1.32) were studied in the post-absorptive rat. Injury raised PEPCK activity by about 70% in 2 h and by over 100% in 4 h, over three times as fast as in animals that had only been handled (controls). The two stresses, both of types commonly imposed in animal experiments, had almost as much effect as injury for the first 2 h, although much less thereafter. The roles of sympathetic stimulation and corticosterone in mediating these rises were studied by using alpha beta-blockers and trilostane respectively as inhibitors. (Trilostane only decreased corticosterone concentrations to a little above control values.) The ether-induced increase was somewhat decreased by alpha beta-blockade, but was only eliminated by combined alpha beta-blockade and trilostane. After injury, however, PEPCK synthesis was unaffected by either alpha beta-blockade or trilostane, although it was decreased by their combined action; and it seems that either corticosterone or sympathetic stimulation was sufficient to stimulate PEPCK synthesis maximally. Stimulation by corticosterone was much greater than reported previously by others, for reasons that are discussed. Sympathetic stimulation may have been mediated by glucagon and cyclic AMP, since injury raised portal glucagon concentrations, and stress and injury raised those of hepatic cyclic AMP. PEPCK synthesis was, however, stimulated despite increases in portal insulin concentration, and was not related to the [insulin]/[glucagon] ratio. Thus stress and injury over-rode normal control mechanisms.

Mortality amongst multiple trauma patients admitted to an intensive therapy unit

A retrospective review of 428 severely injured patients admitted to an intensive therapy unit between 1969 and 1982 was performed. The patients' primary injuries were assessed using the injury severity score (ISS), and subsequent complications using the complications impact index and sepsis score. Between 1969 and 1980 mortality fluctuated between 19% and 29% but rose to 47% (p less than 0.05) during 1981-82 in spite of an unchanged ISS. The increased mortality was confined to ventilated patients surviving more than 5 days from injury and was associated with multiple organ failure and severe infection. The rapid and sustained increase in mortality could not be explained by any obvious change in severity of injury or referral pattern. The only deliberate change in management related to the combination of analgesic/sedative drugs used in ventilated patients. During 1979 to 1982 mortality was 28% in patients given morphine with or without benzodiazepines and 77% in those given morphine and etomidate (p less than 0.0005). After discontinuation of the latter regimen (May 1983) and resumption of the former analgesic/sedative combination, mortality fell to 25% (p less than 0.005). Possible mechanisms leading to increased mortality include adrenocortical insufficiency or depth of anaesthesia.

Trilostane and the normal hypothalamic-pituitary-adrenocortical axis

Trilostane has been used to treat Cushing's syndrome and other adrenocortical disorders. To investigate its effect on the normal adrenal gland, trilostane (initially 240 mg/day) was given to ten healthy men, the dose increasing at weekly intervals by 240 mg/day up to a final dose of 960 mg/day. The drug was well tolerated although one subject withdrew after the first week because of gastrointestinal side effects. Trilostane had no significant effect on aldosterone levels or blood pressure. The mean 24-h urinary free cortisol excretion rose from 14.2 to 22.0 mumol/mol creatinine (P less than 0.01) before and after trilostane 240 mg/day but did not rise thereafter. Early morning serum cortisol and plasma ACTH levels did not change on trilostane. The mean increment in serum cortisol after the i.v. injection of 0.25 mg of ACTH was reduced from 398 nmol/l before trilostane to 287 nmol/l on 240 mg/day and to 291 nmol/l on 960 mg/day (P less than 0.01). Insulin-induced hypoglycaemia while on 960 mg/day produced a maximum increment in serum cortisol of 361 +/- 118 nmol/l (mean +/- SD) although one subject had a subnormal increment of 180 nmol/l (normal greater than 200 nmol/l). Plasma ACTH rose with hypoglycaemia in all cases. We conclude that trilostane has only a minor effect on the normal hypothalamic-pituitary-adrenocortical axis.