Decreased plasma endothelin-1 levels in asymptomatic type I diabetic patients with regional cerebral hypoperfusion assessed by Spect.

The prevalence of stroke is increased in diabetic patients. The vasoconstrictor peptide endothelin-1 (ET-1) has been implicated in the development of cerebral vasospasm after stroke but its role in the physiological regulation of cerebral blood flow (CBF) is not well known. Our aim was to assess the relationship between CBF and plasma ET-1 levels in type I diabetic patients. Regional CBF was assessed semi-quantitatively by 99Tc(m)-hexamethylpropylene-amine-oxime (99Tc(m)-HMPAO) single photon emission computed tomography (SPECT) in 50 cerebral "regions of interest" (ROIs) of 19 type I diabetic patients without clinical evidence of cerebral disease, and 10 healthy control subjects. In both groups, plasma ET-1 levels were measured. Results showed that type I diabetic patients had significantly more hypoperfusion ROIs than control subjects. While up to 68.4% of the type I diabetic patients showed 3 or more hypoperfusion ROIs, only 10% of the control subjects did. Plasma ET-1 levels were lower in the type I diabetes subgroup with 3 or more hypoperfusion ROIs than in the type I diabetes subgroup with less than 3 hypoperfusion ROIs and in the control group. Moreover, an inverse correlation between the number of hypoperfusion ROIs and plasma ET-1 levels (r = 0.47, p = 0.04) was found in the type I diabetes group. It is concluded that plasma ET-1 is decreased in type I diabetic patients with subclinical abnormalities of regional CBF assessed by cerebral SPECT. This fact may reflect a compensatory response to the reduction of the brain perfusion in order to prevent ischemic events in these patients.