Decreased vascular responsiveness to noradrenaline following regular ethanol consumption

Ethanol modulates the neurovascular coupling

Despite some evidence of the underlying molecular mechanisms the neuronal basis of ethanol-induced effects on the neurovascular coupling that forms the BOLD (blood oxygenation level dependent) signal is poorly understood. In a recent fMRI (functional magnetic resonance imaging) study monitoring ethanol-induced changes of the BOLD signal a reduction of the amplitude and a prolongation of the BOLD signal were observed. However, the BOLD signal is assumed to consist of a complex superposition of different underlying signals. To gain insight how ethanol influences stimulus efficacy, oxygen extraction, transit time and vessel-related parameters the fMRI time series from the sensori-motor and the visual cortex were analyzed using the balloon model. The results show a region-dependent decrease of the stimulus efficacy to trigger a post-stimulus neurovascular response as well as a prolongation of the transit time through the venous compartment. Oxygen extraction, feedback mechanisms and other vessel-related parameters were not affected. The results may be interpreted as follows: the overall mechanisms of the neurovascular coupling are still acting well at the moderate ethanol level of about 0.8‰ (in particular the vessel-related parts), but the potency to evoke a neurovascular response is already compromised most obviously in the supplementary motor area responsible for complex synchronizing and planning processes.

Hemodynamics in the immediate post-transplantation period in alcoholic and viral cirrhosis

AIM: To study the hemodynamics in the immediate post transplant period and compare patients with alcoholic vs viral cirrhosis.

METHODS: Between 2000-2003, 38 patients were transplanted for alcoholic cirrhosis and 28 for postviral cirrhosis. Heart rate (HR), central venous pressure (CVP), mean arterial pressure (MAP), pulmonary capillary wedge pressure (PCWP), cardiac index (CI), systemic vascular resistance index (SVRI), pulmonary artery pressure (PAP), and pulmonary vascular resistance index (PVRI) were measured immediately and 24 h post transplantation.

RESULTS: Hyperdynamic circulation persisted at 24 h following transplantation with an elevated CI of 5.4 ± 1.3 L/(min × m²) and 4.9 ± 1.0 L/(min × m²) in the viral and alcoholic groups, respectively, and was associated with a decreased SVRI. Within the first 24 h, there was a significant decrease in HR and increase in MAP; the extent of the change was similar in both groups. The CVP, PCWP, and SVRI increased, and CI decreased in the viral patients, but not the alcoholic patients. Alcoholics showed a lower PVRI (119 ± 52 dynes/(cm⁵× m²) vs 166 ± 110 dynes/(cm⁵× m²), P < 0.05) and PAP (20 ± 7 mmHg vs 24 ± 7 mmHg, P < 0.05) compared to the viral group at 24 h.

CONCLUSION: Hyperdynamic circulation persists in the immediate post-transplant period with a faster improvement in the viral group. Alcoholic patients have a more pronounced pulmonary vasodilatation.

Hyperfibrinolysis in alcoholic cirrhosis: relative plasminogen activator inhibitor type 1 deficiency

BACKGROUND

Over activity of the fibrinolytic system (hyperfibrinolysis) occurs in cirrhosis and has been shown to correlate with the risk of variceal hemorrhage. We have developed a model for assessing acute tissue plasminogen activator (t-PA) release in vivo in man. The aims of the study were to assess the contribution of basal and stimulated t-PA release to hyperfibrinolysis in patients with alcoholic cirrhosis.

METHODS

Bilateral forearm blood flow and plasma fibrinolytic variables were measured in 8 patients with biopsy proven alcohol induced cirrhosis, ascites and portal hypertension, and 8 age and sex matched healthy controls during infusion of bradykinin (100-900 pmol/min; endothelium-dependent vasodilator that releases t-PA) followed by sodium nitroprusside (SNP 2-8 microg/min; a control endothelium-independent vasodilator).

RESULTS

Baseline plasma t-PA antigen concentrations were higher in patients (14+/-2 vs 9+/-1 ng/mL; p<0.05) whereas plasma plasminogen activator inhibitor type-1 (PAI-1) antigen concentrations were similar (59+/-16 vs 55+/-11 ng/mL; p=NS). This resulted in an increased t-PA activity (3+/-1 vs 0+/-0 IU/mL; p<0.05) and reduced PAI-1 activity (9+/-2 vs 21+/-2 AU/mL; p<0.05) indicating a relative deficiency of PAI-1 in patients with cirrhosis. Bradykinin and SNP caused dose-dependent vasodilatation (p<0.001 for both) that did not differ between the two groups. Bradykinin caused a similar release of t-PA antigen (p<0.05 for both) in both patients and controls (24+/-17 vs 23+/-7 ng/100 mL/min; p=ns) without affecting PAI-1 concentrations. Local t-PA activity was increased in patients following acute stimulated t-PA release (5+/-1 vs 3+/-1 IU/mL; p<0.05). SNP caused no significant change in fibrinolytic parameters.

CONCLUSION

Patients with alcoholic cirrhosis have a higher basal plasma t-PA activity because of a failure to increase plasma concentrations of its inhibitor, PAI-1. Furthermore, despite releasing normal amounts of t-PA acutely, higher t-PA activity remained due to the relative deficiency of PAI-1. This suggests that the pathogenesis of hyperfibrinolysis in alcoholic cirrhosis is the result of a relative PAI-1 deficiency and enhanced basal t-PA release.

Bradykinin Does Not Contribute to Peripheral Vascular Tone in Patients With Cirrhosis and Ascites

Bradykinin is an endothelium-dependent vasodilator and inflammatory mediator. The aim of the present study was to examine the effects of bradykinin on peripheral vascular tone in patients with cirrhosis and ascites. Forearm blood flow was measured using venous occlusion plethysmography in 8 patients with biopsy-proven alcohol-induced cirrhosis, ascites, and portal hypertension, and 8 age- and sex-matched healthy controls. On 1 occasion, subjects received an intrabrachial infusion of the selective bradykinin antagonist B9340 (1.5-13.5 nmol/min) followed by a control vasoconstrictor norepinephrine (60-540 pmol/min), and on another occasion bradykinin (100-900 pmol/min) followed by the endothelium-independent vasodilator, sodium nitroprusside (SNP, 2-8 microg/min). Bradykinin and SNP caused a dose-dependent vasodilatation (P < 0.001 for both) that did not differ between the 2 groups. Although norepinephrine caused a similar dose-dependent vasoconstriction in both groups (P < 0.001), B9340 had no effect on forearm blood flow in either group (at 13.5 nmol/min in patients; -5%, 95% CI -13-3). Bradykinin does not provide a major contribution to the maintenance of peripheral vascular tone in patients with cirrhosis and ascites. Our findings also suggest that, in contrast to cardiovascular disease, patients with liver cirrhosis do not have marked endothelial dysfunction.

Inducible nitric oxide synthase activity contributes to the regulation of peripheral vascular tone in patients with cirrhosis and ascites

BACKGROUND

Overexpression of inducible nitric oxide synthase (iNOS) and increased nitric oxide generation may be associated with the hyperdynamic circulation of patients with cirrhosis. We have, for the first time, used the highly selective iNOS inhibitor, 1400W, to determine whether iNOS activity contributes to the regulation of vascular tone in patients with cirrhosis and ascites.

METHODS

Bilateral forearm blood flow was measured using strain gauge plethysmography in eight patients with cirrhosis and ascites, and eight matched healthy volunteers during intrabrachial infusion of 1400W (0.1-1 micromol/min), N(G)-monomethyl-L-arginine (L-NMMA, a non-selective NOS inhibitor; 2-8 micromol), and norepinephrine (a control vasoconstrictor; 60-480 pmol/min).

RESULTS

In patients with cirrhosis, 1400W, L-NMMA, and norepinephrine caused dose dependent reductions in forearm blood flow: peak reductions of 11 (5)%, 37 (4)%, and 48 (5)%, respectively (p < 0.05 for all). In contrast, 1400W had no effect on blood flow (+4 (8)%; NS) in healthy controls despite similar reductions in blood flow with L-NMMA and norepinephrine (39 (5)% and 49 (5)%, respectively; p < 0.05 for both).

CONCLUSIONS

We have, for the first time, demonstrated that 1400W causes peripheral vasoconstriction in patients with cirrhosis but not healthy matched controls. This suggests that iNOS contributes to the regulation of peripheral vascular tone in patients with cirrhosis and ascites, and may contribute towards the hyperdynamic circulation associated with this condition.

Evidence for altered vascular responses to exogenous endothelin-1 in patients with advanced cirrhosis with restoration of the normal vasoconstrictor response following successful liver transplantation

BACKGROUND AND AIMS

There is evidence that dampened responses to endogenous vasoconstrictors contribute to the hyperdynamic circulation that is characteristic of advanced cirrhosis. The aim of this study was to determine whether there is an altered vascular responsiveness to the endothelium derived constricting factor endothelin-1 (ET-1) in patients with decompensated chronic liver disease which might contribute to this abnormal circulatory state, and whether normal endothelin responses are restored following liver transplantation.

METHODS

Using forearm plethysmography, we studied the vascular response to an intra-arterial ET-1 infusion in six patients with end stage cirrhosis, before and after liver transplantation, compared with six normal control subjects. Responses to the selective endothelin A (ET(A)) receptor subtype antagonist, BQ123, were also examined.

RESULTS

The forearm vessels of patients with cirrhosis vasodilated in response to ET-1 infusion while in healthy controls a marked vasoconstriction response was observed (p<0.0001, area under the curve time-blood flow was normal compared with the cirrhosis groups, ANOVA). Prior to commencement of liver transplant surgery, cirrhotic patients were confirmed to have a hyperdynamic circulation with a high cardiac index (4.07 (0.23) l/min/m(2) (normal range 2.8-3.6 l/min/m(2))) and low systemic vascular resistance index (1284 (115) dynxs/cm(5)/m(2) (normal range 1760-2600 dynxs/cm(5)/m(2))). Following transplantation, normal vasoconstrictor responses to ET-1 were restored. Responses to BQ123 were not different in patients with advanced cirrhosis compared with controls.

CONCLUSION

In patients with end stage cirrhosis, ET-1 produces vasodilatation at a dose that causes marked vasoconstriction in normal control subjects. This effect is not attributable to impairment of ET(A) receptor responses. Our findings suggest that altered endothelin responses may contribute to the generalised dilatation of the circulation that occurs in patients with advanced liver disease.

Enhanced vasodilatation to endothelin antagonism in patients with compensated cirrhosis and the role of nitric oxide

BACKGROUND AND AIMS

Patients with advanced cirrhosis have systemic vasodilatation and increased nitric oxide (NO) production despite activated vasopressor systems, including the endothelin system. The aims of this study were to assess the contribution of endogenous endothelin 1 (ET-1) and NO to the maintenance of basal forearm vascular tone in patients with preascitic cirrhosis (n=7) and in age and sex matched healthy controls (n=7).

METHODS

Using venous occlusion plethysmography, forearm blood flow (FBF) responses to subsystemic locally active intra-arterial infusion of BQ-123 (a selective endothelin type A receptor (ET(A)) receptor antagonist; 10 nmol/min) were measured before and during application of an "NO clamp": a balanced co-infusion of L-N(G)-monomethyl-arginine (a selective NO synthase inhibitor) and sodium nitroprusside (an exogenous NO donor) to block endogenous NO production and restore NO mediated basal FBF, respectively.

RESULTS

L-NMMA infusion produced a reduction in FBF (p<0.001) which was similar in both groups. Before applying the "NO clamp", BQ-123 caused an increase in FBF in both groups (p<0.001) that was greater in patients with cirrhosis (p<0.01). During the "NO clamp", BQ-123 induced vasodilatation was abolished in controls and attenuated in patients (p<0.001) but remained significantly greater in patients with cirrhosis (p<0.01).

CONCLUSIONS

These findings indicate a greater ET(A) mediated contribution of endogenous ET-1 to the maintenance of basal forearm vascular tone in patients with preascitic cirrhosis. In addition, enhanced vasodilatation to ET(A) receptor antagonism in cirrhosis cannot be entirely attributed to NO release but is likely to be related to reversal of direct ET-1 mediated tone.

Nitric oxide mediates the reduced vasoconstrictor response to angiotensin II in patients with preascitic cirrhosis

BACKGROUND/AIMS

Altered vascular responses to vasopressor agents contribute to the pathogenesis of the circulatory dysfunction in cirrhosis. This study aims to assess the role of endogenous nitric oxide (NO) in the reduced vascular responsiveness to angiotensin II (ANG-II) in eight patients with preascitic cirrhosis compared with eight age- and sex-matched healthy controls.

METHODS

Forearm blood flow (FBF) responses to sub-systemic, locally-active intra-brachial infusions of ANG-II were measured using venous occlusion plethysmography before and during the application of an 'NO-clamp', a balanced co-infusion of L-N(G)-monomethyl-arginine (a selective NO synthase inhibitor) and sodium nitroprusside (an exogenous NO donor) to block endogenous NO production and restore normal NO-mediated basal blood flow, respectively.

RESULTS

Before applying the 'NO-clamp', ANG-II caused dose-dependent reductions of FBF in both groups (P<0.001) that were significantly attenuated in the cirrhotic patients (P=0.012). In the presence of the 'NO-clamp', the ANG-II-mediated vasoconstriction was enhanced in cirrhotic patients (P<0.01), unchanged in controls, and now similar in both groups.

CONCLUSIONS

This study confirms that vasoconstriction to ANG-II is reduced in patients with preascitic cirrhosis, and suggests that this is principally due to enhanced NO generation mediated by ANG-II.

White coat effect of alcohol

Numerous studies have shown a relationship between alcohol intake and elevated clinic blood pressures (BP). However, there have been few studies on the relationship between alcohol consumption and 24-h ambulatory BP monitoring. This study aimed to determine the relationship between alcohol intake, clinic BP, and 24-h ambulatory BP recordings to determine to what extent a white coat effect may contribute to the relationship between alcohol consumption and BP. Clinical BP and 24-h ambulatory BP were measured in 121 male volunteers aged 50.6 +/- 9.8 years (range, 30-70 years) who consumed between 0 and 2050 g of alcohol per week (mean, 394 +/- 342 g; median, 385 g/week). Supine clinical systolic BP (SBP) was significantly related to alcohol intake (beta = 0.242; P = .007). Alcohol consumption was not related to 24-h mean SBP or diastolic BP (DBP), daytime SBP or DBP, or nighttime SBP or DBP (daytime SBP: beta = 0.02, P = .802). Alcohol intake was significantly related to the difference between clinic SBP and mean daytime SBP (beta = 0.260, P = .004). Twenty-four-hour mean heart rate (HR), daytime mean and nighttime mean HR were strongly associated with alcohol intake (24-h HR: beta = 0.455, P < .001). These results suggest that the association between alcohol consumption and elevated BP is contributed to by a significant white coat effect and that excessive alcohol consumption may be a significant factor in explaining differences between clinic and ambulatory BP measurements.

Role of angiotensin II in regulation of basal and sympathetically stimulated vascular tone in early and advanced cirrhosis

BACKGROUND & AIMS

The renin-angiotensin and sympathetic nervous systems are activated in cirrhosis. This study aimed to establish the role of angiotensin II (ANG II) in the regulation of basal and sympathetically stimulated vascular tone in preascitic cirrhotic patients and patients with diuretic-refractory ascites compared with age- and sex-matched healthy controls.

METHODS

Forearm blood flow (FBF) responses to lower body negative pressure (LBNP) and to subsystemic, intrabrachial infusions of losartan, an angiotensin II type 1 (AT(1)) receptor antagonist, norepinephrine, and ANG II were measured using venous occlusion plethysmography.

RESULTS

In all groups, ANG II and norepinephrine caused dose-dependent reductions in FBF (P < 0.001); responses to norepinephrine were similar across the 3 groups but those to ANG II were less in both cirrhotic groups than in controls (P < 0.01). Losartan caused a dose-dependent increase in FBF only in patients with refractory ascites (P < 0.01). LBNP caused less reduction in FBF in refractory ascites patients than in both preascitic patients and controls (P < 0.01).

CONCLUSIONS

Despite hyporesponsiveness to exogenous ANG II in both early and advanced cirrhosis, endogenous ANG II contributes to the maintenance of basal vascular tone only in advanced cirrhosis. These findings suggest a role of ANG II in the pathogenesis of ascites. Attenuated LBNP responses occurred only in advanced cirrhosis, without apparent interaction with endogenous ANG II.

Lifestyle modifications to prevent and control hypertension. 3. Recommendations on alcohol consumption. Canadian Hypertension Society, Canadian Coalition for High Blood Pressure Prevention and Control, Laboratory Centre for Disease Control at Health Canada, Heart and Stroke Foundation of Canada

OBJECTIVE

To provide updated, evidence-based recommendations concerning the effects of alcohol consumption on the prevention and control of hypertension in otherwise healthy adults (except pregnant women).

OPTIONS

There are 2 main options for those at risk for hypertension: avert the condition by limiting alcohol consumption or by using other nonpharmacologic methods, or maintain or increase the risk of hypertension by making no change in alcohol consumption. The options for those who already have hypertension include decreasing alcohol consumption or using another nonpharmacologic method to reduce hypertension; commencing, continuing or intensifying antihypertensive medication; or taking no action and remaining at increased risk of cardiovascular disease.

OUTCOMES

The health outcomes considered were changes in blood pressure and in morbidity and mortality rates. Because of insufficient evidence, no economic outcomes were considered.

EVIDENCE

A MEDLINE search was conducted for the period 1966-1996 with the terms ethyl alcohol and hypertension. Other relevant evidence was obtained from the reference lists of articles identified, from the personal files of the authors and through contacts with experts. The articles were reviewed, classified according to study design, and graded according to the level of evidence.

VALUES

A high value was placed on the avoidance of cardiovascular morbidity and premature death caused by untreated hypertension.

BENEFITS, HARMS AND COSTS

A reduction in alcohol consumption from more than 2 standard drinks per day reduces the blood pressure of both hypertensive and normotensive people. The lowest overall mortality rates in observational studies were associated with drinking habits that were within these guidelines. Side effects and costs were not measured in any of the studies.

RECOMMENDATIONS

(1) It is recommended that health care professionals determine how much alcohol their patients consume. (2) To reduce blood pressure in the population at large, it is recommended that alcohol consumption be in accordance with Canadian low-risk drinking guidelines (i.e., healthy adults who choose to drink should limit alcohol consumption to 2 or fewer standard drinks per day, with consumption not exceeding 14 standard drinks per week for men and 9 standard drinks per week for women). (3) Hypertensive patients should also be advised to limit alcohol consumption to the levels set out in the Canadian low-risk drinking guidelines.

VALIDATION

These recommendations are similar to those of the World Hypertension League, the National High Blood Pressure Education Program Working Group on Primary Prevention of Hypertension and the previous recommendations of the Canadian Coalition for High Blood Pressure Prevention and Control and the Canadian Hypertension Society. They have not been clinically tested. The low-risk drinking guidelines are those of the Addiction Research Foundation of Ontario and the Canadian Centre on Substance Abuse.

SPONSORS

The Canadian Hypertension Society, the Canadian Coalition for High Blood Pressure Prevention and Control, the Laboratory Centre for Disease Control at Health Canada, and the Heart and Stroke Foundation of Canada. The low-risk drinking guidelines have been endorsed by the College of Family Physicians of Canada and several provincial organizations.

Peripheral vascular tone in patients with cirrhosis: role of the renin-angiotensin and sympathetic nervous systems

OBJECTIVE

The aims of the study were to establish the roles of angiotensin II and of the cardiopulmonary baroreceptor reflex in the regulation of peripheral vascular tone in patients with cirrhosis.

METHODS

Forearm blood flow responses to subsystemic, locally active intrabrachial infusions were measured in patients with Child's Grade C cirrhosis and matched controls using bilateral venous occlusion plethysmography. Responses were determined to the angiotensin II type I receptor antagonist, losartan, noradrenaline, angiotensin II and the nitric oxide synthase inhibitor, L-NG-monomethyl arginine.

RESULTS

Losartan at 30 and 90 micrograms/min caused no significant change in blood flow in controls, but caused 23 +/- 6% and 27 +/- 5% increases in patients respectively (p < 0.001). Lower body negative pressure caused a mean bilateral reduction in forearm blood flow of 20 +/- 4% in controls (p < 0.001) but only tended to reduce flow (9 +/- 5%; p = 0.06) in patients (p < 0.001; controls vs. patients). Noradrenaline, angiotensin II and L-NG-monomethyl arginine caused significant vasoconstriction (p < 0.001) in both patients and controls although angiotensin II caused significantly less vasoconstriction in patients (p = 0.01).

CONCLUSIONS

We conclude that angiotensin II makes an important contribution to basal peripheral vascular tone in patients with cirrhosis in the face of reduced vascular responses to its local administration. In addition, the vasoconstrictor response to cardiopulmonary baroreceptor unloading is attenuated despite normal vascular responses to noradrenaline. These responses are consistent with chronic activation of the renin-angiotensin and sympathetic nervous systems in patients with advanced cirrhosis.

Alcohol, ischemic heart disease, and the French paradox

Many studies have shown either an inverse relation between alcohol intake and ischemic heart disease or a U-shaped curve in which the equivalent of two drinks per day of any kind of alcohol is associated with a decreased incidence of coronary disease compared with no drinks, while higher doses result in an increased risk of infarction and stroke. Although the cardioprotective effects of most alcoholic beverages are probably due to an elevation of high-density lipoprotein as well as the ability of alcohol to prevent platelet aggregation and increased fibrinolysis, there is an increased favorable effect of red wine. The unique cardioprotective properties of red wine reside in the action of flavonoids which are absent in white wine (with the exception of champagne) and sparse in beer (with the exception of dark beers). The best research flavonoids are resveritrol and quercetin, which confer antioxidant properties more potent than alpha-tocopherol. Grape juice has about half the amount of flavonoids by volume as does red wine.

Effect of oral ethanol intake on muscle sympathetic nerve activity and cardiovascular functions in humans

The aim of the present study was to clarify the acute effect of alcohol drinking on muscle sympathetic nerve activity and other cardiovascular variables in young healthy human volunteers. Seven volunteers (25.0 +/- 4.7 years in age, weighing 59.9 +/- 5.9 kg) were instructed to lay down on a bed, and muscle sympathetic nerve activity (MSNA) was microneurographically recorded from the tibial nerve, simultaneously with an electrocardiogram, blood pressure with Finapres and autosphygmomanometer, cardiac output by impedance cardiography, and skin blood flow by laser Doppler flowmetry. After a 1-h rest, the subjects drank alcohol (0.6 g/kg) and were remained in resting position for 105 min. Blood ethanol levels indicated that they were moderately intoxicated. Heart rate constantly increased until 30 min after the ingestion, and maintained a peak level. MSNA was slightly but significantly suppressed just after the ingestion, and was gradually enhanced until the end of the experiment, showing a significant difference from the control level until 40 min in burst rate and until 25 min in total MSNA after the ingestion. Blood pressure showed an abrupt and transient increase at first, then gradual decrease until 30 min after the ingestion, and maintenance of the resting level until the end of the experiment. Cardiac output showed no constant tendency and no significant differences after the ingestion with wide interindividual variation. Skin blood flow increased 15 min after the ingestion.(ABSTRACT TRUNCATED AT 250 WORDS)

High blood pressure due to alcohol. A rapidly reversible effect

The hypothesis that the action of alcohol on blood pressure is rapidly reversible and that its effect is therefore mainly due to very recent alcohol consumption was examined in this study. Five hundred and seventy-seven subjects were screened in an occupational survey. Alcohol consumption, documented with a 1-week retrospective diary was divided into two categories: "recent" and "previous" intake. Recent intake was defined as the amount consumed on days 1, 2, and 3 immediately preceding blood pressure measurement. Previous intake was defined as the amount consumed on days 4, 5, and 6 preceding blood pressure measurement. High recent alcohol intake significantly raised systolic and diastolic blood pressure in both men and women. Previous alcohol intake, however, did not appear to influence blood pressure. We conclude that the effect of alcohol on blood pressure appears to be predominantly due to alcohol consumed in the few days immediately preceding blood pressure measurement, with alcohol consumption before those few days exerting little effect on blood pressure.

Impaired pressor reactivity in cirrhosis: evidence for a peripheral vascular defect

The blood pressure responses to intravenous infusions of norepinephrine and angiotensin II, sympathetic and nonsympathetic vasoconstricting agents, respectively, were measured in 20 patients with cirrhosis (10 Child-Pugh grade A and 10 Child-Pugh grades B or C) and in 20 healthy subjects. The log PD20 (dose of agonist required to raise blood pressure by 20 mm Hg) for norepinephrine was 4.78 +/- 0.36 (mean +/- S.D.) in patients with severe cirrhosis and 4.36 +/- 0.37 in controls, p less than 0.01. Log PD20 for angiotensin II was 3.16 +/- 1.06 in patients with severe cirrhosis and 1.97 +/- 0.74 in controls, p less than 0.01. Cardiovascular responses to selective sympathetic agonists were measured in 10 other cirrhotic patients (all Child-Pugh grades B or C) and in 10 healthy controls. Log PD20s for phenylephrine, an alpha-1 adrenoceptor agonist, and for alphamethylnorepinephrine; an alpha-2 adrenoceptor agonist, were increased in cirrhosis (phenylephrine = 5.35 +/- 0.49 vs. 4.95 +/- 0.35, p less than 0.05; alphamethylnorepinephrine = 4.05 +/- 0.26 vs. 3.44 +/- 0.55, p less than 0.001). In contrast, log CD20 (dose of agonist required to raise the heart rate by 20 beats/min) for isoproterenol, a beta-adrenoceptor agonist, was similar in cirrhotic patients and controls (2.81 +/- 0.38 vs. 2.94 +/- 0.45, p = 0.49). These studies demonstrate that pressor reactivity to both sympathetic and nonsympathetic agonists is impaired in severe cirrhosis, that the impaired sympathetic responses are not caused by generalized sympathetic desensitization and that the site common to the four agonists with impaired responses is the peripheral vascular smooth muscle.

Factors determining the acute pressor response to alcohol

The pressor response to acute alcohol loading is variable and the factors influencing it are unknown. Data from 34 standardized alcohol loading studies were analysed to try to identify any factor(s) that might predict the pressor response to oral alcohol. The maximum blood pressure rise following an acute alcohol load was assessed for each subject over a 4 hour period. Age, weight, recent alcohol intake, baseline blood pressure, pulse rate and serum gamma glutamyl transferase levels were entered, as the independent variables, into a multiple linear regression analysis with the maximum blood pressure response as the dependent variable. Alcohol consumption in the week prior to the study predicted the systolic blood pressure pressor response to acute alcohol loading. None of the independent variables entered had any predictive value for diastolic or mean arterial blood pressure response.

Effects of regular alcohol consumption on 24 hour ambulatory blood pressure recordings

1. Regular consumption of 1 g/kg of alcohol for 4 days did not significantly alter mean 24 h blood pressures compared with a similar period when dextrose was consumed to match caloric intake. 2. In contrast, the variability of diastolic blood pressure was increased by regular alcohol consumption. 3. Increased blood pressure variability in response to the stress of blood pressure measurement may contribute to the observed association between hypertension and alcohol consumption.

Alcohol intoxication blunts sympatho-adrenal activation following brain injury

In 46 patients experiencing traumatic brain injury, we studied the interactions of alcohol intoxication and severity of neurologic dysfunction on the resulting sympathetic nervous system activation. Sixty percent of the variation in norepinephrine (p less than 0.0001) and more than 50% of the variation in epinephrine (p less than 0.0001) were due to the initial ethanol concentrations and extent of brain injury assessed by the admission Glasgow Coma Score (GCS). As brain function deteriorated plasma cathecholamines rose (p less than 0.0001), but ethanol qualitatively and quantitatively modified this observation. The magnitude of the sympathetic response to worsening neurologic function was progressively diminished in association with increasing ethanol levels, i.e., the inverse relationship of GCS values with both norepinephrine and epinephrine was flattened. In comatose patients (GCS less than 8) increasing ethanol levels was associated with progressively decreasing norepinephrine and epinephrine responses (p less than 0.04), such that catecholamines were reduced by 80 to 90% at ethanol concentrations approaching 400 mg/dl (87.0 mmol/l). However, the impact of ethanol on the degree of sympathetic nervous system activation depended upon the degree of injury; the apparent ethanol suppression was greatest in patients with the most severe neurologic dysfunction (GCS 3 or 4), but it diminished as neurologic function improved. We conclude that the presence of alcohol appears to modify the rise in catecholamine levels following traumatic brain injury in a dose-dependent manner and alters the relationship between neurologic dysfunction and SNS activation. These alterations may have profound effects on patient morbidity in the immediate post-accident period.

Alcoholism and panic disorder: is the comorbidity more than coincidence?

Studies on alcoholic patients have found a higher than expected prevalence of panic disorder, and suggest a positive correlation between the level of alcohol consumption and severity of anxiety. Conversely, there is an increased prevalence of alcoholism among patients with panic disorder and their blood relatives. A comparison of symptoms, physiological and neurochemical changes known to occur in both alcohol withdrawal and panic disorder reveals a degree of similarity between the 2 conditions. Based on the data, we propose that the chemical and cognitive changes occurring as the result of repeated alcohol withdrawals may kindle and condition coincidence of panic attacks in susceptible individuals. Implications of our postulates for treatment of alcohol withdrawal and panic disorder in alcoholics and for future studies are discussed.

Alcohol consumption and blood pressure. An Italian study

We studied the relationship between alcohol consumption and arterial pressure in 1,190 subjects of both sexes aged between 18 and 63 years who were examined during the course of a program of preventive medicine organized by Centro Diagnostico Italiano. In 711 subjects who were not requested to alter their usual alcohol consumption we found a significant relationship between alcohol consumption and systolic arterial pressure, b + SE(b), 4.6 +/- 2.1 mmHg/100 g ethanol/day. In particular, males who were heavy drinkers (greater than or equal to 50 g ethanol/day) presented significantly higher systolic pressure levels than the other men, d +/- SE(d), 3.7 +/- 1.6 mmHg, whereas no significant differences were observed among the various classes of women subdivided according to alcohol intake (only 4.6% of the women consumed greater than 50 g ethanol/day). On the other hand, in 479 subjects who were requested to abstain from alcohol consumption during the three days preceding the examination, no significant relation was found between alcohol intake and arterial pressure. The difference between the systolic pressure levels of the male heavy drinkers and those of the male moderate and non-drinkers was only 0.1 mmHg. Excessive alcohol consumption, in this case, mainly in the form of wine, was therefore associated with higher systolic pressure levels. However, it seems that abstaining from alcohol for even a brief period may modify this relation considerably.

Ethanol as a reinforcer for rats: factors of facilitation and constraint

This review examines some particular approaches that have been used to investigate factors that facilitate or constrain the self-administration of ethanol by rats. A technique for increasing ethanol self-administration in rats, the prandial drinking method, was examined and the effect of body-weight reduction on drug intake was discussed. Emphasis was placed on how ethanol intake may be controlled by processes in addition to the direct pharmacological actions of the drug in the CNS. These processes may be physiological. Evidence was presented for a relationship between activity in the renin-angiotensin system and the self-administration of ethanol. These processes may also be environmental. Using the place-conditioning technique, demonstrations were presented of how the context or situation in which ethanol is experienced may determine whether preference or aversion for the drug develops. Such a diversity in the factors that can potentially control ethanol intake may complicate the identification of the causes of alcohol abuse, but this same diversity also holds out greater hope that manipulations may be found to reduce excessive drinking in humans.

The effects of acute and chronic ingestion of ethanol on the autonomic nervous system

Evidence is reviewed linking clinical effects of ethanol with actions on the sympathetic and parasympathetic nervous systems. The studies reported include a series of investigations by the authors. Acutely, ethanol causes peripheral vasodilation and may also result in changes in heart rate and blood pressure. Ethanol may contribute to acute problems which may present clinically, including micturition syncope, accidental hypothermia and facial flushing. However, increased sympathetic nervous activity plays a role in causing hypertension and other symptoms during ethanol withdrawal in chronic alcoholics. Some chronic alcoholics may have neuropathy involving sympathetic nerves, and this can result in distal sweating loss and occasionally in orthostatic hypotension. Also, hypothalamic lesions associated with Wernicke's encephalopathy may result in hypothermia. Neuropathy involving parasympathetic nerves in not uncommon in alcoholics with other evidence of nervous system damage, but it is generally asymptomatic. Occasionally, vagal neuropathy may cause disorder of gastrointestinal motility, and neuropathy affecting the sacral innervation may be a factor in alcoholic impotence.

Plasma [3H]-noradrenaline kinetics and blood pressure following regular, moderate ethanol consumption

Normotensive male volunteers (n = 8) either abstained from ethanol for 4 days or consumed 66 g of ethanol per day in an open, crossed, random order study. Mean arterial pressures rose by an average of 5.4 mmHg following the ethanol phase of the study (P less than 0.001). Plasma noradrenaline (NA) concentration was higher during ethanol ingestion (P less than 0.01), principally because of a significant reduction in NA clearance of -1.51 l min-1 m-2 (P less than 0.05). In contrast, NA spillover or release rates did not significantly differ between the two study periods. Total plasma calcium levels were significantly lower (P less than 0.05) following the ethanol compared to the control period. These data do not appear to support the proposition that regular alcohol consumption raises blood pressure by producing a generalised increase in sympathetic activity.