Plasma adrenaline and noradrenaline concentrations in diabetic patients with and without autonomic neuropathy at rest and during sympathetic stimulation

Abstract

Summary. Plasma concentrations of adrenaline and noradrenaline were measured radio-enzymatically in nine patients with diabetic autonomic neuropathy, seven diabetic patients without autonomic neuropathy and nine normal subjects, in the recumbent position and after standing. Furthermore, in six patients with autonomic neuropathy and in the normal subjects, plasma noradrenaline and adrenaline concentrations were determined during and after cyclo-ergometer exercise. No differences in plasma adrenaline concentrations were found at any time in the study. Basal plasma noradrenaline levels were significantly lower in diabetic patients with autonomic neuropathy than in the non-neuropathic diabetics or healthy control subjects. After standing, plasma noradrenaline rose to significantly higher levels in both control and diabetic subjects without neuropathy than in the patients with autonomic neuropathy. During exercise (up to 100 W load), plasma noradrenaline rose to similar levels in healthy controls and in patients with diabetic neuropathy. These data indicate that in diabetic autonomic neuropathy there is reduced peripheral neurosympathetic tone at rest but a normal response to moderate exercise. Blunted neurosympathetic responses to standing seem to be a consistent feature of diabetic autonomic neuropathy, particularly in those patients with severe postural hypotension.Key words: Plasma catecholamines, adrenaline, noradrenaline, sympathetic nervous activity, diabetes mellitus, autonomic neuropathy, postural stimulation, orthostatic hypotension, muscular exercise.Autonomic neuropathy in diabetes mellitus produces a variety of different symptoms and signs due to variable involvement of the sympathetic and parasympathetic branches of the autonomic nervous system [6,14,16].Plasma catecholamine levels have been investigated in only a few studies in recent years, as a possible humoral index of sympathetic function in complicated or uncomplicated diabetes. While the results obtained from these studies indicate that plasma catecholamine levels in uncomplicated diabetes are normal, the frequency of sympathetic deficiency, as reflected by subnormal plasma noradrenaline concentrations, in diabetic autonomic neuropathy and its possible importance in relation to symptoms, such as postural hypotension, is less clear [1,9,10,12,19]. This uncertainty could be due, at least in part, to difficulties in the accurate measurement of catecholamine responses and also in the characterization of diabetic autonomic neuropathic syndromes.The present investigation was aimed at evaluating peripheral sympathetic function and reactivity to appropriate stimuli, such as standing and muscular exercise, in diabetic patients with autonomic neuropathy, compared with diabetics without neuropathy and normal subjects. For this purpose, the presence of diabetic autonomic neuropathy was ascertained from a series of clinical and instrumental evaluations. Plasma adrenaline and noradrenaline concentrations, measured by a sensitive and specific radio-enzymatic me...

The influence of beta‐adrenoceptor blocking drugs with and without intrinsic sympathomimetic activity on the hormonal responses to hypo‐ and hyperglycaemia.

“…In spite of a marked increase of adrenaline concentrations the recovery from hypoglycaemia was slow following propranolol and bradycardia and ectopic beats were observed (Deacon et al, 1977). These results imply that propranolol treatment carries some risk in insulin-dependent diabetics (Kotler et al, 1966;Wright et al, 1979) who have reduced adrenergic responses due to autonomic neuropathy (Caviezel et al, 1980;Barnett et al, 1980 A, during insulin-(0.1 U/kg body weight) induced hypoglycaemia and after an oral glucose load (100 g) on heart rates in volunteers (n = 8). Mean ± s.e.mean results.…”

Disparity of autonomic control in type 2 diabetes mellitus

“…By design, our findings were obtained in patients with type 2 diabetes who had no evidence of neuropathy, because this could interfere with autonomic neural control and its effects [33][34][35][36]. We used previously accepted criteria [19,20], as well as clinical examination and vasopressor responses, to exclude somatic and autonomic neuropathy.…”

Plasma Norepinephrine in Sensory Diabetic Polyneuropathy

“…In a series of 100 nonketotic diabetic patients, Cryer et al (23) showed mean basal and posturally stimulated plasma NE was normal, but subsets of neuropathic patients were identified as having exaggerated or reduced sympathoadrenal re • sponses. Caviezel et al (24) found basal and posturally stimulated NE to be reduced in diabetic patients who had autonomic and painless somatic neuropathy. Christensen (25) found plasma catecholamines to be reduced in diabetic patients with peripheral neuropathy in one study, whereas in another study he found no difference in plasma NE between neuropathic and nonneuropathic diabetic patients (26).…”