Evidence for alpha 1-adrenoreceptor hyperresponsiveness in hypotensive cirrhotic patients with ascites

Cirrhosis with ascites is often characterized by arterial hypotension associated with increased plasma norepinephrine levels. Clinical evidence suggests a decreased sensitivity to norepinephrine in this clinical setting, indicating a potential derangement of alpha 1 adrenoreceptors. The aim of the present study was to evaluate the reactivity of the alpha 1-adrenoreceptor, using phenylephrine, a selective alpha 1 receptor agonist. First, we evaluated the pupillar response to the intraconjunctival administration of the agonist. Hypotensive cirrhotic patients showed a trend to a more marked and prolonged response, compared with age-matched healthy controls. Second, we studied the response of alpha 1-adrenoreceptors in the peripheral vasculature by administering iv phenylephrine to a similar group of patients. A significantly greater and longer lasting pressor response was observed in hypotensive cirrhotic patients (p less than 0.0001 vs. healthy controls). Our results indicate that in this group of patients, there is a rather peculiar situation, characterized by alpha 1-adrenoreceptor hyperresponsiveness in the presence of high levels of circulating norepinephrine. This finding could be related to biochemical abnormalities within the peripheral sympathetic nervous system endings.