Mechanics of the carotid artery wall and baroreflex sensitivity after acute ethanol administration in young healthy volunteers

Abstract

The effects of ethanol administered orally (300 mg/kg in 250 ml of water) or intravenously (7.5 mg.min(-1).kg(-1) in 250 ml of saline over 40 min) on common carotid haemodynamics, wall mechanics and baroreflex sensitivity were compared with the effects of the intravenous infusion of 250 ml of saline. Ethanol or saline was administered to 10 healthy volunteers after 30 min of supine rest, and measurements were obtained 40 min (median; range 34-46 min) after administration. After ethanol administration, the plasma alcohol level rose from 0 to 0.3+/-0.07 g/l. Mean arterial blood pressure had risen slightly at 20 min, but was normalized by 40 min, the time at which the haemodynamic study was performed. Heart rate decreased after infusion of either saline or alcohol, but was unchanged after oral ethanol administration. Both oral and intravenous ethanol administration were associated with significant decreases in baroreflex sensitivity, carotid shear stress and blood velocity, compared with resting values, while the mean carotid artery diameter was increased, and blood viscosity and mean blood flow were unchanged. No changes were observed in these parameters after saline administration. Ethanol, administered either intravenously or orally, increased the stiffness of the carotid artery and decreased the pulsatility (systo-diastolic changes) of its diameter. A direct, statistically significant correlation was found between the decrease in shear stress and the decrease in baroreflex heart rate control sensitivity after both modes of alcohol administration, while no such correlation was found between the increase in the Peterson elastic modulus and the decrease in carotid diameter pulsatility on the one hand or the decrease in baroreflex sensitivity on the other. In conclusion, reduced shear stress associated with vasodilatation of the carotid artery wall may contribute to the decrease in baroreflex sensitivity observed after acute ethanol administration.

Potentiated sympathetic and hemodynamic responses to alcohol in hypertensive vs. normotensive individuals

“…In hypertension, baroreflex dysfunction is limited primarily to impaired regulation of HR, whereas sympathetic modulation of peripheral circulation is less disrupted [33]. Previous studies have shown that alcohol attenuates baroreflex control of HR [24,34], probably through an increased stiffness and decreased pulsatility of the carotid artery [35]. In our study, HR responses to alcohol were similar in normotensive and hypertensive individuals despite greater blood pressure increase in the latter group.…”

Long-term hypoxia alters ovine fetal endocrine and physiological responses to hypotension

“…One could speculate that ethanol may have played a role in blunting the heart rate response to hypotension. Although to our knowledge there are no studies in the literature examining the effect of ethanol on fetal baroreceptor function, there are abundant data in adult animals and humans to suggest that ethanol can attenuate baroreflex-mediated heart rate function (7,29). The apparent dissociation between baroreflex mediation of endocrine and cardiovascular responses in the fetus observed in the present study will serve as an area of future study.…”

Associations of metabolic variables with arterial stiffness in type 2 diabetes mellitus: focus on insulin sensitivity and postprandial triglyceridaemia

“…However, we assessed fasting, postprandial and mean 24‐h triglyceride concentrations, and found that these were not significantly associated with any of the outcome variables in this study. Among healthy subjects, the association between triglyceride concentrations and arterial stiffness is also weak [15,34] or absent [35]. We conclude therefore that an increase in arterial stiffness is an unlikely explanation for the association between hypertriglyceridaemia and cardiovascular risk in type 2 diabetes.…”