Observations in man of hypoglycaemia during selective and non-selective beta-blockade.

The acute hypoglycaemic reaction is accompanied by a rise in systolic and a slight fall in diastolic blood pressure and a tachycardia. In contrast, during beta-blockade with propranolol there is a rise of both systolic and diastolic blood pressures and bradycardia. Restoration of blood glucose to normal is delayed. With metoprolol there is a lesser increase in diastolic blood pressure and a slight tachycardia. Restoration of the blood glucose to normal is little delayed. When patients liable to hypoglycaemia require a beta-blocking agent, it is suggested that a selective blocker such as metoprolol should be used.

A method of teaching epidemiology in the clinical setting.

It is important to provide an epidemiological presence when teaching clinical medicine to undergraduate medical students in order to supply the underlying facts about disease. A series of pictorial or tabular presentations which together make up a 'master set' of Data Boards has been designed to give the medical student a visual picture of epidemiology. Each Data Board is constructed in such a way that it can be readily interpreted by a medical student at the bedside or in similar situations to those where he is expected to interpret clinical signs and symptoms of disease. The present use of Data Boards in clinical teaching is described and suggestions for future applications are made.

Why palpate the radial artery?

The palpability of the radial-artery wall was assessed before death in 43 patients and compared with the histology of the artery at necropsy. There was no relationship between the degree of palpability and the histological changes of atheroma or of Mönckeberg's sclerosis, or the presence of clinical vascular disease. It is suggested that palpation of the wall of the radial artery provides no useful clinical information.

Hormonal and substrate responses during recovery from hypoglycaemia in man during beta 1-selective and non-selective beta-adrenergic blockade.

Recovery from acute hypoglycaemia induced by the injection of insulin has been examined in six human subjects under control conditions, under non-selective beta blockade (propranolol) and under selective beta 1 blockade (metoprolol). The normal blood glucose recovery was biphasic with an initial rapid and a slower subsequent phase of recovery. The early recovery mechanism was unaffected by either form of beta blockade, but with propranolol the late phase of recovery was significantly prolonged. Rises in blood lactate and plasma free fatty acids following hypoglycaemia were markedly reduced by propranolol but to a much lesser degree with metoprolol. The counterregulatory hormonal responses of glucagon, cortisol and growth hormone were augmented appropriately for the prolonged hypoglycaemia associated with propranolol. Non-selective beta adrenergic blockade with propranolol is associated with an impairment of the late phase of blood glucose recovery from hypoglycaemia. The possible mechanisms of this impairment are discussed.

Peripheral blood cell changes in response to acute hypoglycaemia in man.

Peripheral white and red blood cell changes were studied in response to acute insulin-induced hypoglycaemia in six normal, six splenectomized and five sympathectomized (tetraplegic) subjects. The normal subjects were restudied during beta (propranolol) and beta 1-selective (metoprolol) adrenergic blockade. In the normal subjects a lymphocytosis immediately followed the acute hypoglycaemic reaction (R) with a neutrophilia 2 h later. The early lymphocytosis was absent in sympathectomized subjects (P less than 0.001) and reduced under beta blockade (P less than 0.02) in normal subjects, indicating mediation via an adrenergic mechanism. The later neutrophilia from R + 60 min was not abolished by adrenergic blockade or preceding sympathectomy; the enhanced response with propranolol was associated with an elevated plasma cortisol. Haemoglobin, packed cell volume and total erythrocyte count rose maximally at R in all groups except the sympathectomized subjects in whom all parameters declined progressively from basal values. These peripheral erythrocytes changes appear to be mediated via an adrenergic mechanism which is unaffected by beta adrenergic blockade and which does not involve splenic contraction.

Cholinergic manifestations of the acute autonomic reaction to hypoglycaemia in man.

1. The effects of insulin-induced hypoglycaemia on pupil size, parotid salivary secretion and sweating were studied in seven normal volunteers. 2. Hypoglycaemia was associated with an acute stimulation of parotid salivary secretion and of sweating, synchronous in onset with the rise in heart rate. There was no clear evidence of concurrent pupillary constriction.