Skeletal muscle blood flow and neurovascular reactivity in liver disease

Abstract

SUMMARY There was no significant difference in forearm muscle blood flow, measured by the clearance of 133Xenon when 38 patients with liver disease were compared with 38 normal subjects. Patients with a clinically hyperdynamic circulation, finger clubbing, and previous portocaval anastomoses were included in the study.The changes in forearm skeletal muscle blood flow and pulse rate caused by a head-up tilt of 70 degrees were measured in 15 patients with chronic liver disease and 15 age-matched controls. Head-up tilting resulted in significantly less peripheral vasoconstriction and tachycardia in the group with liver disease than in the control group.These results suggest an impairment of baroreceptor-mediated sympathetic reactivity in liver disease. Such a defect might explain the relative rarity of hypertension in patients with cirrhosis.A hyperdynamic circulation is often found in patients with liver disease (Kontos, Shapiro, Page Mauck, and Patterson, 1964;Murray, Dawson, and Sherlock, 1958) and increased blood flow to the hand has been demonstrated in cirrhosis (Abramson and Lichtman, 1937;Martini and Hagemann, 1956). As it is generally accepted that blood flow to the hand is almost entirely cutaneous (Kontos et al, 1964), skin blood flow would appear to be increased in liver disease.The major components of forearm blood flow in normal subjects at rest are those to skin and skeletal muscle (Cooper, Edholm, and Mottram, 1955). Kontos et a! (1964) have presented indirect evidence that in some patients with cirrhosis there are increases in both muscle and skin blood flow whereas in others only one of these two components is increased. However, there has been no direct evaluation of skeletal muscle blood flow in liver disease.The factors responsible for the circulatory changes of liver disease are unknown, many unsuccessful attempts having been made to identify a humoral vasodilator substance. We have investigated neurovascular responsiveness in patients with chronic liver disease in order to determine a possible alter- Received for publication 8 February 1973 native explanation for these circulatory changes. Head-up tilting from the horizontal position is a powerful stimulus to the baroreceptors in the low pressure vascular compartments in the chest. Firing of these baroreceptors results in reflex vasoconstriction of blood vessels in the forearm and a concomitant tachycardia. These reflexes are transmitted via the sympathetic nervous system. MethodsSkeletal muscle blood flow was measured using the technique of Lassen (Lassen, Lindbjerg, and Munck, 1964). All subjects were supine and had neither eaten nor smoked for at least two hours. Studies were performed at room temperature (23-26°C).133Xenon gas, 150-250 ,Ci, dissolved in not more than 0.15 ml of saline was injected directly into the brachioradialis muscle. The injection was given over a 15-second period and the needle left in situ for a further 15 seconds. At least 15 minutes was allowed to elapse before recording was commenced.The clearance of xenon w...

Sympathetic Nervous Activity and Renal and Systemic Hemodynamics in Cirrhosis: Plasma Norepinephrine Concentration, Hepatic Extraction, and Renal Release

“…It has been suggested that patients with cirrhosis have impaired baroreceptor-mediated sympathetic nervous reactivity (10). The present results do not indicate a general defect in NE-mediated vasoconstriction in these patients as they were able to maintain arterial blood pressure during tilting and the kidney vasculature even capable of further contraction.…”

“…an elevated plasma volume (1, 2), cardiac output (3, 4), heart rate (5, 6), and possibly muscle perfusion (6) whereas arterial blood pressure (1, 5) and renal blood flow (5, 7,8) are decreased. The mechanisms of changes in vascular resistance in cirrhosis are unknown.The rise in heart rate during various autonomic reflex stimulation tests has been found significantly reduced in cirrhosis (9), and impaired vasoconstriction in skin and muscles during a vertical tilt has been demonstrated even in patients with compensated cirrhosis (10). It has been…”

Impairment of Blood Pressure Control in Patients with Liver Cirrhosis during Tilting: Study on Adrenergic and Renin-Angiotensin Systems

“…The parallel increase of norepinephrine and arterial pressure after tilting suggests that the adrenergic system can achieve an ade quate vascular response in the short term, and a reduced activity of baroreceptors [4] is therefore unlikely. The lack of heart rate ac celeration after tilting could be due to a pre valent peripheral adrenergic stimulation.…”

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

“…An alternative means of assessing adrenergic responsiveness is by reflex stimu- lation of the sympathetic nervous system. The pressor response to head-up tilt is reported as impaired (21,22) or unimpaired (23).…”