The plasma ET-1 level is markedly and significantly increased in patients with MS. Neither the cause of such an increase nor the pathogenetic role is known.

ABSTRACT.Purpose: To compare thirst, drinking behaviour, and endothelin-1 (ET-1) plasma levels between vasospastic and non-vasospastic subjects. Methods: We compared 67 subjects with a primary vasospastic syndrome with 64 age-and sex-matched non-vasospastic control subjects. A detailed medical history was recorded, including a questionnaire containing queries about thirst and drinking behaviour, history of migraine or unspecific headache, history of episodes of low blood pressure, and smoking habits. Body mass index (BMI) was calculated and blood samples were drawn for ET-1 measurements. Results: Subjects with a vasospastic syndrome reported a reduced desire to drink and a lower estimated quantity of daily fluid intake, more often forgot to drink, more often had both migraine and unspecific headache, more often had episodes of low blood pressure, and had an increased plasma level of ET-1. These features differed statistically significantly between the two groups. There was also a nonsignificant trend among vasospastic subjects to smoke less and to have a smaller BMI. Conclusion: A reduced desire to drink is found frequently among vasospastic subjects.

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We postulate that the Susac syndrome is a manifestation of the vasospastic syndrome.