Cardiovascular responses evoked by mild cool stimuli in primary Raynaud's disease: the role of endothelin.

In control subjects and in subjects with primary Raynaud's disease, sudden sound evokes the pattern of the alerting response, which includes cutaneous vasoconstriction and vasodilatation in forearm muscle. However, whereas this pattern of response habituates on repetition of the sound stimulus in control subjects, both cutaneous vasoconstriction and muscle dilatation persist in subjects with primary Raynaud's disease. The aim of the present study was to test whether a similar disparity exists between control subjects and those with primary Raynaud's disease for the response to mild cool stimuli, and whether the cutaneous response is accompanied by the release of endothelin-1 (ET-1). In nine subjects with primary Raynaud's disease and in nine matched controls, the left hand was placed in cool water at 16 degrees C for 2 min five times on each of three experimental sessions on days 1, 3 and 5, with blood being taken from the venous drainage of the cooled hand before and at the end of the second session. In response to the first cool stimulus in Session 1, the subjects with primary Raynaud's disease showed a decrease in digital cutaneous vascular conductance (DCVC) in both the right and left hands, as indicated by a laser Doppler recording of erythrocyte (red cell) flux divided by arterial pressure, and six of the nine subjects showed an increase in forearm vascular conductance (FVC), as indicated by forearm blood flow measured by plethysmography divided by arterial pressure. On repetition of the stimulus in Session 1, there was no change in the magnitude of the increase in FVC, but the evoked decreases in DCVC became more prolonged in both the right and the left hand. Similar responses occurred in Sessions 2 and 3; in Session 2, the ET-1 concentration increased from a baseline value of 2.15+/-0.26 fM to 2.72+/-0.37 fM after five stimuli. There was no habituation of the increase in FVC over Sessions 1, 2 and 3, judging from the mean changes in each session. Control subjects also showed a decrease in DCVC in both hands, and in eight out of nine subjects there was an increase in FVC in response to the first cool stimulus in Session 1. However, on repetition of the stimulus in Session 1, the increase in FVC habituated, while there was no prolongation of the decrease in DCVC; in addition, the ET-1 concentration did not change in Session 2 in response to the stimulus (2.07+/-0.28 compared with 2.29+/-0.30 fM). Further, the increase in FVC habituated over the three sessions, such that there was a mean decrease in FVC in Session 3. These results indicate that, in subjects with primary Raynaud's disease, there is impairment of the ability of the central nervous system to allow habituation of the cardiovascular components of the alerting response evoked by mild cooling, as with the response to sound. We propose that persistence of the cutaneous vasoconstriction of the alerting response, coupled with increased release of ET-1 secondary to vasoconstriction, prolongs such vasoconstriction and eventually leads to vasospasm.     

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.     

Effect of dazoxiben, a thromboxane synthetase inhibitor on skin-blood flow following cold challenge in patients with Raynaud''s phenomenon

The effects of dazoxiben on finger-blood flow in response to cold challenge were studied in normal subjects and patients with Raynaud's phenomenon. In normal subjects concentrations of TXB2 and 6-oxo-PGF1 alpha were measured in blood taken from dorsal hand veins following cold challenge. In a parallel multicentre study we examined the effects of dazoxiben on finger temperature and capillary blood cell velocity in patients with Raynaud's phenomenon. Dazoxiben did not affect finger arterial inflow at rest or during cold challenge in patients or controls. However in both groups, recovery was quicker after cold challenge on dazoxiben treatment. In patients median flow was 5 ml (100(-1) ml) min-1 (range 1-10) v. 2 (0.5-15), P less than 0.05 dazoxiben v. placebo at 15 min after cold challenge. However, in normal subjects this did not prove to be statistically significant. In normal subjects there was a fall in TXB2 concentrations and relative rise in 6-oxo-PGF1 alpha following dazoxiben treatment indicating redirection of prostaglandin endoperoxides towards synthesis of PGI2. Comparison of the sum-total output of each eicosanoid following treatment with dazoxiben revealed a 65% reduction in TXB2 concentrations (P less than 0.025 compared with placebo) and a 40% increase in 6-oxo-PGF1 alpha concentrations (P less than 0.05 compared with placebo). However a simultaneous increase in concentrations of FPA indicated generation of thrombin, probably at the needle tip. Long-term treatment with dazoxiben resulted in no significant change in finger-skin temperature or capillary blood cell velocity, duration, or severity of attacks of Raynaud's phenomenon.     

Adrenergic supersensitivity in Parkinsonians with orthostatic hypotension

The adrenergic status was studied through evaluation of platelet alpha 2-adrenoceptor number [( 3H]yohimbine binding sites), plasma catecholamine levels and blood pressure response to noradrenaline infusion in three groups of subjects (1) Parkinsonians with orthostatic hypotension; (2) Parkinsonians without orthostatic hypotension; and (3) control subjects. In Parkinsonians with orthostatic hypotension, systolic and diastolic blood pressures significantly (P less than 0.05) decreased from 144 +/- 9 and 76 +/- 6 mmHg in the lying position to 95 +/- 12 and 60 +/- 7 mmHg after 5 min standing. In these patients, noradrenaline plasma levels were significantly low (62 +/- 11 pg ml-1, (P less than 0.05) when compared with controls (219 +/- 13 pg ml-1) whereas no difference was noticed in Parkinsonians without orthostatic hypotension (195 +/- 14 pg ml-1). The noradrenaline dose required for a 25 mmHg increase in systolic blood pressure was significantly (P less than 0.01) lower in Parkinsonians with orthostatic hypotension (0.19 +/- 0.03 microgram kg-1) when compared with Parkinsonians without orthostatic hypotension (0.86 +/- 0.11 microgram kg-1) or with controls (0.68 +/- 0.1 microgram kg-1). Platelet alpha 2-adrenoceptor number was higher in Parkinsonians with orthostatic hypotension (313 +/- 52 fmol mg-1 protein) than in Parkinsonians without orthostatic hypotension (168 +/- 9 fmol mg-1 protein) or in controls (175 +/- 4 fmol mg-1 protein) with no change in Kd. This study demonstrates that in patients with Parkinson's disease, orthostatic hypotension is associated with an increase in both vascular sensitivity to noradrenaline and platelet alpha 2-adrenoceptor number.(ABSTRACT TRUNCATED AT 250 WORDS)     

Beta2-adrenoceptor density on membranes and on intact mononuclear cells in essential hypertension

Alterations in the status or in the regulation of adrenoceptors may contribute to essential hypertension. This could be studied using the recently introduced radio-ligand binding techniques to characterize the adrenoceptors on human peripheral blood cells. The present study shows that patients with essential hypertension have a twofold increase of beta 2-adrenoceptor density on intact mononuclear cells as compared to normotensive controls: 859 +/- 260 (n = 10) vs. 420 +/- 119 (n = 10) maximal binding sites for (+/-) 125-Iodocyanopindolol expressed as molecules per cell (P less than 0.001). Furthermore, there is a highly significant correlation (r = 0.86) between the calculated mean arterial blood pressure and the beta 2-adrenoceptor density over a wide range of normal and increased blood pressure. These findings could only be demonstrated with intact mononuclear cells but not with membrane fractions. No difference was found in receptor affinity between patients with essential hypertension and normotensive controls. Thus, essential hypertension is combined with a higher beta 2-adrenoceptor density on intact mononuclear cells which might represent, for example, an increased density of prejunctional beta 2-adrenoceptors. Mean arterial blood pressure is positively correlated with beta 2-adrenoceptor density over a wide range of blood pressure in normotensives and hypertensives. The expression of beta 2-binding sites on the cell surface is possibly altered in essential hypertension resulting in a disparity between intracellular and extracellular binding sites as compared with normotensives.     

Dazoxiben, a thromboxane synthetase inhibitor, in Raynaud's phenomenon

Dazoxiben, a specific thromboxane synthetase inhibitor, was evaluated in 21 patients with Raynaud's phenomenon in a double-blind, placebo-controlled crossover experiment. Total fingertip blood flows were measured by plethysmography and capillary blood flows were measured by 133Xe disappearance rate. Subjects were studied in both a warm (28 degrees) and a cold (20 degrees) room. Arteriovenous (AV) shunt flow was estimated by subtraction of capillary flow from total flow. Ex vivo production of thromboxane B2 (TXB2) and 6-keto PGF1 alpha was determined by specific radioimmunoassay in serum from venous blood incubated for 1 hr (37 degrees). Plasma concentrations of TXB2 and 6-keto PGF1 alpha were also monitored. Dazoxiben (100 mg 4 times a day for 14 days) inhibited ex vivo TXB2 production (from 463.1 +/- 69.9 to 101.8 +/- 13.4 ng/ml/hr; (means +/- SE], enhanced ex vivo 6-keto PGF1 alpha production (from 1.38 +/- 0.05 to 3.76 +/- 0.18 ng/ml/hr), reduced plasma TXB2 concentration (from 88.1 +/- 13.9 to 38.8 +/- 5.9 pg/ml). There were no changes in plasma concentration of 6-keto PGF1 alpha. Dazoxiben did not improve total digital blood flow, capillary flow, AV shunt flow, or forearm blood flow at 28 degrees or 20 degrees. There was no subjective improvement in frequency or severity of Raynaud's attacks (assessed by patient diaries). It is concluded that dazoxiben is a potent and specific thromboxane synthetase inhibitor capable of altering arachidonic acid metabolism, but is of little or no benefit in the treatment of Raynaud's phenomenon.     

Carvedilol in treating primary pulmonary hypertension patients: effect on severity of cardiac failure,degree of pulmonary hypertension,concentration of catecholamines in blood plasma and dependence of cyclic AMP synthesis in lymphocytes on beta-adrenergic receptors

AIM: To evaluate carvedilol effect on clinical state, norepinephrine (NE) and epinephrine (E) plasma concentration and lymphocyte beta 2-adrenoreceptor dependent cAMP synthesis in patients with primary pulmonary hypertension (PPH). MATERIAL AND METHODS: 14 patients with PPH were included in the study; 9 patients were treated by carvedilol; 5 patients were in the control group. The primary efficiency parameters were submaximal exercise measured by 60 min walk test, systolic pulmonary artery pressure (SPAP) measured by Doppler echocardiography, heart rate (HR) measured by 24-hour ECG-monitoring. RESULTS: One month carvedilol treatment of PPH patients resulted in a significant HR reduction. There was a tendency to SPAP decrease, the 6-minute walk test results improved in IIINYHA patients. CONCLUSION: Carvedilol therapy improves clinical state and evoked lymphocyte beta 2-adrenoceptor resensitization in PPH patients.     

Differential effects of epinephrine and norepinephrine on cAMP response and g(i3)alpha protein expression in cultured sympathetic neurons.

The effect of 24-h pretreatment with epinephrine (EPI) or norepinephrine (NE) on alpha(2)- and beta-adrenoceptor agonist-induced, cAMP responses and G(i3)alpha-protein expression was studied in primary cultures of rat superior cervical ganglionic (SCG) neurons. SCG neurons, 10 to 12 days in culture, accumulated cAMP when stimulated with the beta-adrenoceptor agonist isoproterenol and the preferential beta(2)-adrenoceptor antagonist ICI 118,551 blocked this response. Similarly, the preferential alpha(2)-adrenoceptor agonist UK14,304 inhibited forskolin-stimulated cAMP accumulation, implying that cultured SCG neurons possess functional alpha(2)- and beta(2)-adrenoceptors. A 24-h treatment of SCG neurons with EPI or NE induced desensitization of the cAMP response to the beta-adrenoceptor agonist isoproterenol. Simultaneously, EPI treatment increased the maximal inhibitory cAMP response to the alpha(2)-adrenoceptor agonist UK14,304 and NE was without effect. Immunoblotting analyses of G(i3)alpha subunits revealed that 24-h EPI but not NE treatment induces a 3- to 4-fold increase in the expression of G(i3)alpha subunits. Furthermore, EPI-induced up-regulation of alpha-subunit expression can be blocked by the preferential beta(2)-adrenoceptor antagonist ICI 118,551 but not by the preferential beta(1)-adrenoceptor antagonist CGP 20712A. Our results suggest that changes in alpha(2)-adrenoceptor responsiveness induced by EPI may involve activation of beta(2)-adrenoceptors that influence the expression of inhibitory G proteins. Thus, primary cultures of sympathetic neurons by possessing functional alpha(2)- and beta-adrenoceptors may be a suitable model system to study the signaling mechanisms of "cross talk" between these adrenoceptor subtypes, which are known to play a central role in cardiovascular function.     

Measurement of soluble adhesion molecules in primary Raynaud’s phenomenon and in Raynaud’s phenomenon secondary to connective tissue diseases

Adhesion molecules play a role in the inflammation and pathogenesis of vascular diseases. In 13 patients with primary Raynaud's phenomenon, 19 with Raynaud's phenomenon associated with connective tissue disease, and 16 control subjects, we measured plasma levels of soluble forms of intercellular adhesion molecule-1, vascular cell adhesion molecule-1, E-selectin, and von Willebrand factor. Patients with secondary Raynaud's phenomenon had plasma levels of soluble forms of intercellular adhesion molecule- 1, vascular cell adhesion molecule-1, E-selectin, and von Willebrand factor which were significantly higher than in those with primary Raynaud's phenomenon and controls, while no difference was observed between patients with primary Raynaud's phenomenon and controls. Within the group with secondary Raynaud's phenomenon, the strongest correlations were between soluble forms of intercellular adhesion molecule-1 and both E-selectin, (r=0.67, P<0.001) and von Willebrand factor (r=0.58, P<0.01). In none of the three groups were the levels of soluble adhesion molecules and von Willebrand factor changed by exposure of hands to cold, although all patients had a definite vasospasm. In conclusion, this study indicates that primary Raynaud's phenomenon is not associated with elevation of soluble adhesion molecules and von Willebrand factor. Prospective studies are now required to investigate the role of these molecules as predictors of secondary diseases.     

Platelet alpha-2 adrenoceptors and the menstrual cycle

To clarify further the suggested influence of menstrual cycle phase on platelet alpha 2-adrenoceptors, we carried out cross-sectional studies in 77 subjects in a clinical trial of weight control strategies. Blood samples were drawn at baseline and after 6 weeks of diet, behavior modification, and exercise, a program that resulted in a mean weight loss of 4.5 kg. For the analyses, 42 premenopausal women were divided into four groups according to the week of menstrual cycle at the time of blood sampling. At baseline, there was no significant difference in mean platelet alpha 2-adrenoceptor numbers among the four groups. At week 6 accompanying the weight loss, there was a significant increase in the platelet alpha 2-adrenoceptor number for all groups. Despite the fact that the women were at a different phase of the menstrual cycle than at baseline, there was again no significant difference in mean platelet alpha 2-adrenoceptor number. Mean baseline platelet alpha 2-adrenoceptor number in the premenopausal women (113.7 +/- 5.5 fmol/mg protein) did not differ from values in 12 postmenopausal women (113.7 +/- 12.0 fmol/mg protein), four women with hysterectomies (105.9 +/- 8.9 fmol/mg protein), or 19 men (101.8 +/- 6.2 fmol/mg protein). Numbers at 6 weeks also did not differ. We conclude that the menstrual cycle has minimal effects on platelet alpha 2-adrenoceptor number and should not confound clinical studies of platelet alpha 2-adrenoceptors.     

ENALAPRIL IN RAYNAUD''S PHENOMENON

The effect of enalapril in the treatment of Raynaud's phenomenon was assessed in a prospective double-blind cross-over trial in 17 patients (nine primary Raynaud's, eight Raynaud's associated with scleroderma). Each patient received 20 mg enalapril daily and placebo for 3 weeks with a 2-week washout period in between. The severity and frequency of Raynaud's attacks were measured subjectively by a diary count and objectively by measurement of finger systolic pressure changes in response to cooling (cold challenge test). Enalapril was associated with a reduction in the frequency of Raynaud's attacks, especially in patients with primary Raynaud's, compared with placebo, but there was no effect on the cold challenge test. We conclude that enalapril, like other vasodilator drugs, helps the symptoms of Raynaud's phenomenon, especially in patients with idiopathic or primary disease.     

Effect of a beta 2-adrenoceptor stimulation on hyperglycemia-induced endothelial dysfunction

To investigate whether beta(2)-adrenoceptors exist on endothelial cells and whether a beta(2)-adrenoceptor stimulation might prevent the development of hyperglycemia-induced endothelial dysfunction, porcine aortic endothelial cells (PAECs) were cultured and chronically exposed to either 5 mM D-glucose ("normoglycemia") or 20 mM D-glucose ("hyperglycemia"), with or without 100 nM salbutamol in absence or presence of beta(2)-adrenoceptor antagonist ICI 118,551 [1-[2,3-(dihydro-7-methyl-1H-inden-4-yl)oxyl]-3-[(1-methylethyl)-amino]-2-butanol] or beta(1)-antagonist metoprolol. For osmotic control, PAECs were exposed to 15 mM L-glucose. We measured nitric oxide release using the met-hemoglobin assay and assessed beta-adrenoceptor density and subtypes by radioligand binding. Furthermore, we determined intracellular NADH and NADPH using high-performance liquid chromatography. High D-glucose concentrations but not L-glucose led to significantly reduced basal and stimulated nitric oxide release. Chronic salbutamol treatment significantly antagonized the impairment of the nitric oxide response, which was inhibited by ICI 118,551 but not by metoprolol. The number of giant cells was significantly increased in hyperglycemia, which could be prevented by salbutamol. Binding of the radioligand (-)-[(125)I]iodocyanopindolol revealed a total beta-adrenoceptor density of 29.8 +/- 3.7 (normoglycemic) and 30.3 +/- 3.6 (hyperglycemic) fmol/mg protein. Displacement by ICI 118,551 revealed beta-adrenoceptor subtype distribution with 30.3 +/- 4.4 (normoglycemic) and 29.1 +/- 3.8% beta(2)-adrenoceptors. NADH production increased in hyperglycemia, which was completely prevented by salbutamol. We conclude that hyperglycemia in PAEC induces endothelial dysfunction with impaired nitric oxide release and that this can be prevented by beta(2)-adrenoceptor stimulation.     

A pathogenic role of visceral fat beta 3-adrenoceptors in obesity.

Increased release of free fatty acids (FFA) from visceral fat cells to the portal venous system may cause several metabolic disturbances in obesity. However, this hypothesis and the underlying mechanism remain to be demonstrated. In this study catecholamine-induced lipid mobilization through lipolysis in omental adipose tissue was investigated in vitro in 25 markedly obese subjects (body mass index range 35-56 kg/m2) undergoing weight reduction surgery and in 19 nonobese subjects (body mass index range 20-28 kg/m2) undergoing cholecystectomy. Release of FFA and glycerol, induced by norepinephrine or adrenergic receptor subtype-specific agonists, were determined in isolated omental fat cells. The obese subjects had higher fat cell volume, blood pressure, plasma insulin levels, blood glucose, plasma triglycerides, and plasma cholesterol than the controls. There was evidence of upper-body fat distribution in the obese group. The rate of FFA and glycerol response to norepinephrine was increased twofold in the cells of obese subjects; no significant reutilization of FFA during catecholamine-induced lipolysis was observed in any of the groups (glycerol/FFA ratio near 1:3). There were no differences in the lipolytic sensitivity to beta 3- or beta 2-adrenoceptor specific agonists between the two groups. However, beta 3-adrenoceptor sensitivity was approximately 50 times enhanced (P = 0.0001), and the coupling efficiency of these receptors was increased from 37 to 56% (P = 0.01) in obesity. Furthermore, the obese subjects demonstrated a sixfold lower alpha 2-adrenoceptor sensitivity (P = 0.04). beta 3-Adrenoceptor sensitivity, but not alpha 2-, beta 1-, or beta 2-adrenoceptor sensitivity, correlated with norepinephrine-induced lipolysis (r = -0.67, P = 0.0001) and fat cell volume (r = -0.71, P = 0.0001). In conclusion, catecholamine-induced rate of FFA mobilization from omental fat cells is accelerated due to elevated rate of lipolysis in obesity, mainly because of an increased beta 3-adrenoceptor function, but partly also because of a decreased alpha 2-adrenoceptor function. This promotes an increased release of FFA to the portal system, which may contribute to the parallel metabolic disturbances observed in upper-body obesity.     

Terbutaline-induced desensitization of human lymphocyte beta 2-adrenoceptors. Accelerated restoration of beta-adrenoceptor responsiveness by prednisone and ketotifen.

We investigated, in 36 healthy volunteers, the effects of prednisone and ketotifen on recovery of lymphocyte beta 2-adrenoceptor density (determined by (-)-125iodocyanopindolol binding) and responsiveness (assessed by lymphocyte cyclic AMP [cAMP] responses to 10 microM (-)-isoprenaline) after desensitization by the beta 2-agonist terbutaline. Terbutaline (3 X 5 mg/d) decreased lymphocyte beta 2-adrenoceptor density by approximately 40-50%; concomitantly, lymphocyte cAMP responses to 10 microM (-)-isoprenaline were significantly reduced. After withdrawal of terbutaline beta 2-adrenoceptor, density and responsiveness gradually increased, reaching predrug levels after 4 d. Prednisone (1 X 100 mg orally) accelerated beta 2-adrenoceptor recovery; only 8-10 h after administration of the steroid beta 2-adrenoceptor density and cAMP responses to (-)-isoprenaline had reached values not significantly different from pretreatment levels. Similar effects were obtained with ketotifen (2 mg; thereafter 2 X 1 mg/d for 4 d): 24 h after application of the drug beta 2-adrenoceptor density and cAMP responses to (-)-isoprenaline had reached pretreatment levels. Furthermore, ketotifen simultaneously applied with terbutaline completely prevented terbutaline-induced decrease in lymphocyte beta 2-adrenoceptor density and responsiveness. Prednisone (1 X 100 mg orally) or ketotifen (2 mg; thereafter 2 X 1 mg/d for 2 d) had no significant influence on lymphocyte beta 2-adrenoceptor density in healthy volunteers not pretreated with terbutaline, but shifted the ratio high-to-low affinity state of the lymphocyte beta 2-adrenoceptor toward high affinity state. We conclude that glucocorticoids as well as ketotifen can accelerate recovery of density and responsiveness of lymphocyte beta 2-adrenoceptors desensitized by long-term treatment with beta 2-agonists. Such an effect may have clinical implications for preventing tachyphylaxis of asthmatic patients against therapy with beta 2-agonists.     

An objective test for the diagnosis and grading of vasospasm in patients with Raynaud's syndrome.

1. Reliable objective tests for the diagnosis and grading of vasospasm would be helpful in the assessment of patients with Raynaud's syndrome. 2. Measurements of finger blood flow at local finger temperatures from 32 degrees C down to 20 degrees C did not reliably distinguish between patients with Raynaud's syndrome and matched control subjects. 3. Using laser Doppler flowmetry to detect blood cell flux in fingertip skin, there was no significant difference (Wilcoxon's signed rank test) in the finger systolic blood pressure of 28 patients with Raynaud's syndrome and their matched controls when the fingers were warm at 32 degrees C. 4. Absence of flux was considered to indicate complete vasospasm and the degree of cooling required to abolish flux indicated the severity of the vasospastic condition in an individual patient. 5. Finger cooling for 5 min did not significantly alter finger systolic blood pressure in the control subjects, but abolished blood cell flux in the fingertip skin of 27 of the 28 patients with Raynaud's syndrome. 6. A grading scale was derived from the flux measurements. There was a significant correlation (r = 0.75, P less than 0.001) between the grading of disease severity as judged by the flux test and the clinical grade as assessed before the laboratory visit. 7. There was one false-negative result in the 28 patients with Raynaud's syndrome tested and no false-positive results in 28 matched control subjects. 8. This type of testing may prove helpful in the diagnosis and grading of vasospastic disorders.     

Dynamic exercise-induced increase in lymphocyte beta-2-adrenoceptors: abnormality in essential hypertension and its correction by antihypertensives

We compared the effects of acute stimulation of sympathetic activity by dynamic exercise on a bicycle on lymphocyte beta 2-adrenoceptor density and 10 mumol/L (-)-isoprenaline-evoked lymphocyte cyclic adenosine monophosphate increases in normotensive volunteers with those in patients with essential hypertension. In normotensive subjects exercise increased lymphocyte beta 2-adrenoceptors by about 100%. This effect seems to be a beta 2-dependent process, since it is prevented by propranolol (5 mg administered intravenously) and the beta 2-selective antagonist ICI 118,551 (25 mg t.i.d. orally for 2 weeks) but not by the beta 1-selective antagonist bisoprolol (2.5 mg administered intravenously). In patients with essential hypertension who have elevated lymphocyte beta 2-adrenoceptors, dynamic exercise caused only marginal beta 2-adrenoceptor changes, suggesting an impairment of the acute beta-adrenoceptor regulation. Normalization of blood pressure by antihypertensive treatment resulted in a significant fall in lymphocyte beta 2-adrenoceptors and in a restoration of exercise-induced beta 2-adrenoceptor increases. It is concluded that in essential hypertension the impairment of beta-adrenoceptor regulation is directly linked to the elevated blood pressure.     

Mechanism of the vascular angiotensin II/alpha2-adrenoceptor interaction

alpha(2)-Adrenoceptors potentiate vascular responses to angiotensin II. The goal of this study was to test the hypothesis that the phospholipase C (PLC)/protein kinase C (PKC)/c-src/phosphatidylinositol 3-kinase (PI3K) pathway contributes to the vascular angiotensin II/alpha(2)-adrenoceptor interaction. In rats in vivo, intrarenal infusions of angiotensin II (10 ng/kg/min) increased renal vascular resistance by 5.8 +/- 0.5 units, and this response was enhanced (p < 0.05) to 9.1 +/- 1.2 units by UK-14,304 [5-bromo-N-(4,5-dihydro-1H-imidazol-2-yl)-6-quinoxalinamine; 3 microg/kg/min; alpha(2)-adrenoceptor agonist]. Intrarenal infusions of U-73122 [1-[6-[[(17beta)-3-methoxyestra-1,3,5(10)-trien-17-yl]amino]-hexyl]-1H-pyrrole-2,5-dione; 3 microg/min; PLC inhibitor], GF109203X [bisindolylmaleimide I; 10 microg/min; PKC inhibitor], CGP77675 [1-(2-{4-[4-amino-5-(3-methoxyphenyl)pyrrolo[2,3-d]pyrimidin-7-yl]phenyl}ethyl)piperidin-4-ol; 5 microg/min; c-src inhibitor], and wortmannin (1 microg/min; PI3K inhibitor) abolished the angiotensin II/alpha(2)-adrenoceptor interaction. In isolated perfused rat kidneys, angiotensin II (0.3, 1, and 3 nM) increased perfusion pressure (by 15 +/- 8, 39 +/- 4, and 93 +/- 9 mm Hg, respectively), and UK-14,304 (1 microM) potentiated these responses (to 36 +/- 4, 67 +/- 7, and 135 +/- 17 mm Hg, respectively). This angiotensin II/alpha(2)-adrenoceptor interaction was abolished by U-73122 (10 microM), GF109203X (3 microM), CGP77675 (5 microM), and wortmannin (0.2 microM). Preglomerular microvascular smooth muscle cells expressed phospholipase (PLC)-beta(2), PLC-beta(3), c-src, phospho(tyrosine 416)-c-src, and PI3K. In these cells, angiotensin II (0.1 microM) and UK-14,304 (1 microM) per se did not increase phospho-c-src; however, the combination of angiotensin II plus UK-14,304 doubled phospho-c-src, and this interaction was abolished by U-73122 (10 microM) and GF109203X (3 microM). In conclusion, the PLC/PKC/c-src/PI3K pathway may contribute importantly to the interaction between alpha(2)-adrenoceptors and angiotensin II on renal vascular resistance.     

Laser Doppler velocimetry of fingertips during heat provocation in normals and in patients with Raynaud's phenomenon

Measurements of Laser Doppler flow were performed on the fingertip during heating in a group of normals and in a group of patients with different types of Raynaud's phenomenon. During heating a group of 24 normals was distinguished from a group of 29 primary Raynaud's patients. A group of 17 patients with secondary Raynaud's phenomenon due to scleroderma and 8 patients with arteriographically proven severe vascular occlusive disease of the fingers showed a significantly lower response in comparison to the two above-mentioned groups. Patients with or without slight or severe trophic skin lesions were identified. In patients with scleroderma the maximal vasodilation during heating was inversely related to the number of organs affected. In conclusion, measurements of the hyperaemia during heating may play a role in determining the degree of obstructive vascular involvement in Raynaud's phenomenon.