Objectives-The main objective was to study the acute vascular effects in the hands of normal healthy subjects of a complex vibration spectrum similar to that generated by many industrial hand held tools. The effects of repeated bouts of vibrations and alterations in the intensity of vibration were also studied. Methods-Blood flow was measured by venous occlusion plethysmography with strain gauges. Vibration across a frequency range of 0'4 to > 4000 Hz was generated by a pneumatic chisel and applied to the right hand. Blood flow was measured in both middle fingers, both big toes, or both forearms before, during, and after a two minute period of vibration. Systolic pressure of a finger and heart rate were also measured. Results-Vibration was associated with a significant bilateral reduction in finger and toe blood flow (P < 0.01 and P < 0.03) and a significant increase in heart rate (P < 0.05) but had no effect on forearm blood flow. The finger response was not abolished by repeated bouts of the vibration but was initially most notable during the first minute of vibration. Increasing the intensity of vibration delayed recovery. Conclusions-Hand vibration causes a generalised increase in sympathetic tone in the heart and extremities. This may be a factor in the development of vasospastic disease in habitual users of hand held industrial vibrating tools.

SUMMARY1. Emotional sweating was induced in normal subjects by mental arithmetic at environmental temperatures of 29 and 260 C and estimated from continuous records of body weight loss.2. The sweat output from four independent regions of the body -(a) the head and neck, (b) the arms and legs, (c) the trunk, and (d) the hands and feet -was studied separately, the remainder of the body being covered in each case by plastic bags. The evaporative water loss from each skin region increased markedly during mental arithmetic.3. The sweat contribution from each region was a substantial fraction of the total body sweat response and appeared to be roughly proportional to the calculated number of sweat glands in each region.4. There is no evidence from these experiments to indicate that the sweat glands of the skin of the hands and feet behave differently to those of the skin of the rest of the body in response to emotional stress.

Venous occlusion plethysmography has been used to measure sympathetic vasoconstrictor responses in the feet and hands to a deep breath and body cooling and to assess blood flow variability. Measurements were made in 14 non-diabetic control subjects and 52 diabetic patients, 30 of whom had evidence of peripheral neuropathy. All the measurements were significantly reduced in the feet of patients with neuropathy. Vasoconstrictor responses were not significantly impaired in the hands of these patients. Cardiovascular autonomic function was assessed in the same subjects by standard tests of reflex heart rate responses and compared to sympathetic vasoconstrictor function as determined by the response to a deep breath. Eighteen of the 30 diabetic patients with peripheral neuropathy had impairment of both cardiovascular and sympathetic vasoconstrictor function. Five had normal vasoconstrictor but impaired cardiovascular responses and two had normal cardiovascular but impaired vasoconstrictor function. It may therefore be important to assess both systems in diabetic patients.

Patients with type II diabetes may have impaired peripheral autonomic function at diagnosis.

Objective-To determine circulating endothelin-1 levels (ET-1) in patients with primary or secondary associated Raynaud's phenomenon (RP) under resting conditions and in response to cold provocation. Methods-Patients were categorised as primary RP (18) or scleroderma associated RP (14). Finger blood flow was measured by venous occlusion plethysmography at finger temperatures of 32°C and 24°C. Vasospasm was detected as a finger systolic pressure of 0 mm Hg after standardised provocative cooling. Severity of vasospasm was assessed by the level of cooling required to provoke spasm. Plasma ET-1 levels were measured in antecubital blood withdrawn under baseline conditions (finger 32°C) and at the point of vasospasm. Measurements were also made in 19 matched control subjects. Results-Finger blood flow was lower in patients with RP than in controls, with no diVerence between the two RP groups. Vasospasm occurred in all patients with RP but not in any control subjects and a grading system of severity was established. Baseline plasma ET-1 levels were similar in patients with RP and controls. Increases in ET-1 levels at the point of vasospasm in patients or corresponding timepoint in controls were also similar. There was no significant diVerence between the ET-1 levels in the two RP subgroups when the fingers were warm or when vasospasm was present. Conclusions-These results do not support the hypothesis that ET-1 plays a part in the pathogenesis of RP. Objective testing is a useful adjunct to the clinical diagnosis of RP and allows assignment of a severity grade.