Effect of sympathectomy on the response to adrenaline of the blood vessels of the skin in man

Mechanisms in the return of vascular tone following sympathectomy in man

The response of the hand blood vessels has been determined to the intra-arterial administration of ephedrine and reserpine and to the intravenous administration of norepinephrine before and at intervals after sympatheetomy. The constrictor response to ephedrine slowly disappeared over a period of six weeks, during which time the vessels became increasingly sensitive to norepinephrine. The dilator effect of reserpine was abolished early after sympatheetomy but became slowly re-established over the subsequent three months. The findings suggest that residual vasoconstrictor fibers cannot account for the return of tone following sympatheetomy but that changes in the catecholamine content of the tissue and increasing sensitivity to both these and circulating amines may be closely related to this phenomenon.

EFFECTS OF BRETYLIUM AND GUANETHIDINE ON HUMAN HAND AND FOREARM VESSELS AND ON THEIR SENSITIVITY TO NORADRENALINE

Infusions of bretylium and guanethidine into the brachial artery of normal subjects caused a fall in forearm and hand blood flow followed by a sustained increase in flow. The constrictor phase was attributed to catechol amine release since it was blocked by phenoxybenzamine. A slight and transient increase in response of the hand vessels to noradrenaline was seen after bretylium in the early constrictor phase before sympathetic block was complete. Guanethidine produced a more definite and sustained increase in the response of the hand vessels to noradrenaline. It is concluded that the phenomenon of tolerance which is conspicuous with bretylium and negligible with guanethidine is unlikely to be due to the rapid onset of hypersensitivity of the peripheral vessels.

Cold-induced changes in plasma norepinephrine, epinephrine and dopamine concentrations in patients with Raynaud's phenomenon

To investigate the role of the sympathetic system in Raynaud's phenomenon, which has not yet been elucidated, we measured the levels of norepinephrine, epinephrine and dopamine before, immediately and 30 min after the cold pressor test in plasma from 17 patients with primary, 6 with secondary Raynaud's phenomenon and 19 volunteers, matched for age and sex. Patients had significantly low baseline epinephrine (0.13 +/- 0.02 vs 0.37 +/- 0.04, nmol/l, p less than 0.001, mean +/- S.E.), but normal norepinephrine and dopamine (norepinephrine: 1.77 +/- 0.16 and 2.06 +/- 0.18; dopamine: 0.10 +/- 0.01 and 0.11 +/- 0.02, patients and controls). Immediately after the cold test norepinephrine significantly increased (p less than 0.001) in patients (2.42 +/- 0.22) and controls (3.24 +/- 0.28); epinephrine increased in patients (0.18 +/- 0.02, p less than 0.02); dopamine did not show any significant change (0.13 +/- 0.01 and 0.13 +/- 0.02, patients and controls). In the recovery period, while norepinephrine and epinephrine returned to baseline in both groups, dopamine increased in controls (0.21 +/- 0.04, p less than 0.005) but remained unchanged in patients (0.11 +/- 0.01). We conclude that there is no sympathetic overactivity in Raynaud's phenomenon and propose a role for circulating dopamine in post-ischaemic vasodilatation as an explanation for the particular behaviour of dopamine.

Raynaud's disease: reduced hand blood flows with normal blood viscosity

Hand blood flows and the blood and plasma viscosities were measured in patients with Raynaud's disease in an attempt to identify the mechanism of the episodic vascular insufficiency. Using venous occlusion plethysmography the following observations were made: (1) the hand blood flows were significantly less than in normals at 32 degrees, 27 degrees and 20 degrees C; (2) the percentage decrease in flow with cooling was greater in normals and (3) cooling of one hand from 32 degrees to 27 degrees C caused an abnormal decrease in flow through the contralateral hand. Using a rotational viscometer the blood and plasma viscosities were found to be normal at both high and low shear rates. The percentage increase in the blood viscosity with cooling from 35 degrees to 25 degrees was also normal. These studies demonstrate an increased constrictive response of the cutaneous vasculature of the hand to both local and reflex stimulation, and exclude a rheological abnormality, under conditions similar to those of the present study.

Blood hyperviscosity with reduced skin blood flow in scleroderma

The vascular complications of scleroderma have previously been attributed to the progressive obliteration of small vessels. Our study was carried out to determine whether abnormalities of blood viscosity occur in this disease, thereby contributing to the ischaemic process. Blood viscosity was measured in 20 patients using a rotational viscometer. At a high rate of shear, blood hyperviscosity was found in 35% of the patients and at a low rate of shear, in 70%. In addition there was a significant increase in the plasma viscosity which implicates changes in plasma proteins (fibrinogen, immunoglobulins) as causing the hyperviscosity. Measurement of the hand blood flow by venous occlusion plethysmography showed reduced flow at 32 degrees , 27 degrees , and 20 degrees C. A unique finding was a delayed recovery of the blood flow after cooling. These observations suggest that the increased resistance to blood flow in skin affected by scleroderma may be caused by an interaction between the occlusive vascular lesion and blood hyperviscosity. In addition, blood flow patterns and hyperviscosity could help distinguish scleroderma from primary Raynaud's disease.

Idiopathic orthostatic hypotension controlled with a monoamine oxidase inhibitor and 9-alpha-fluorohydrocortisone

A case of orthostatic hypotension with autonomic failure is presented, and the patient's clinical response to the combined regime of a monoamine oxidase inhibitor and 9-alpha-fluorohydrocortisone is discussed. This therapy provided a relatively convenient means of alleviating the patient's symptoms and appears to be of considerable value in the management of orthostatic hypotension. However, close patient supervision is essential when these drugs are used as they cause hypertension in the supine position in subjects with poor baroreceptor function.

Vascular responses in the hands of patients suffering from migraine

The response of the hand blood vessels to a measured, controlled cold stimulus was determined, using venous occlusion plethysmography, in normal subjects and patients who suffered from migraine. The resting level of hand blood flow was found to be higher in the patients, but the percentage fall in flow that resulted when the cold stimulus was applied was less than in the normal subjects. The hand blood vessels of the patients responded to intra-arterial noradrenaline and tyramine in a normal fashion.

The effect of ethyl alcohol and chlorpromazine on the response of the hand blood vessels to cold

1. The response of hand blood flow to a measured cold stimulus was determined using venous occlusion plethysmography in normal subjects, before and after orally administered alcohol, and in patients on chlorpromazine therapy.2. The average resting hand blood flow of the patients taking chlorpromazine, as well as the constriction of these blood vessels to cold, was the same as in the normal subjects.3. Oral alcohol caused a rise in resting hand blood flow in the normal subjects and also modified the response of the hand blood vessels to cooling.4. A patient with a completely denervated hand was also studied. Oral alcohol did not increase the blood flow through the part, but it modified the hand vascular response to cold.5. These results suggest a diminished reactivity of the hand blood vessels to cold in the presence of alcohol.

Modification of the vasoconstrictor action of sympathomimetic agents by bretylium tosylate and tranylcypromine in man

1. The vasoconstrictor actions of tyramine, methylamphetamine and ephedrine on the blood vessels of the human hand have been found to be potentiated by administration intra-arterially of the adrenergic neurone blocking agent, bretylium tosylate.2. One mechanism suggested for the enhancement of vasoconstriction is that bretylium possesses monoamine oxidase inhibiting activity, which, in the case of tyramine, is protective both to the sympathomimetic agent and the intra-neuronal transmitter which it releases. In the case of methylamphetamine and ephedrine, which are not substrates for the enzyme, protection of the intra-neuronal transmitter alone might occur, accounting for the lesser degree of potentiation of the effect of these amines by bretylium.3. Comparison of the influences of bretylium and the monoamine oxidase inhibitor, tranylcypromine, on the vasoconstrictor action of the sympathomimetic agents shows a similar pattern of enhancement in the presence of both these drugs.4. Tranylcypromine caused enhancement of the response of the hand vessels to noradrenaline, and this action could contribute to its potentiation of the effect of the sympathomimetic amines.5. For a monoamine oxidase inhibiting action of bretylium to be effective in potentiating the constrictor actions of the sympathomimetic agents on the hand blood vessels at a time when reflex sympathetic activity is blocked it is necessary to postulate that these drugs and reflex nerve activity act either on different compartments of the transmitter store or by different release mechanisms.

Inhibition of Levarterenol by Intra-Arterial Phenoxybenzamine in Man

The infusion of 1.2 mg. phenoxybenzamine into the brachial artery of healthy adults was followed by a marked reduction in constrictor responses in the corresponding hands to infused levarterenol and to sympathetic stimuli.

The antagonism of the vascular effects of 5-hydroxytryptamine by BOL 148 and sodium salicylate in the human subject

2-Bromo-(+)-lysergic acid diethylamide (BOL 148) is a specific antagonist of the constrictor response of the forearm and hand blood vessels to intra-arterial infusions of 5-hydroxytryptamine. This has been shown to be a direct action in the tissue concerned, since the antagonism was as effective when the drug was given by local arterial injection as when given intravenously. Sodium salicylate is also a specific antagonist of 5-hydroxytryptamine, but its action is indirect, occurring only when the general serum level was raised above 10 or 20 mg.%; local limb concentrations of 30 to 40 mg.% had no antagonistic effect. The mechanism of the antagonistic effect of salicylate is not known. It is not related to the associated hyperventilation but is possibly due to the secondary release of, or synergism with, some other substance, probably a hormone.

Vasomotor responses in the extremities of subjects with various neurologic lesions. I. Reflex responses to warming

Vascular responses to warming were studied in hemiplegic patients and after sympathectomy, using venous occlusion plethysmography of foot and leg. Comparisons were made with corresponding age groups. The pattern of response was essentially unchanged in hemiplegic patients, but was altered substantially where sympathetic pathways had been interrupted.