Plasma endothelin-1 levels depress optic nerve head circulation detected during the glucose tolerance test.
OBJECTIVE
To determine the relationship between the changes in optic nerve head (ONH) circulation and the level of plasma endothelin-1 (ET-1) during the glucose tolerance test (GTT).


METHODS
Twenty-six healthy volunteers with normal GTT and 15 patients with mild hyperglycemia and abnormal GTT were studied. The ONH circulation [square blur rate (SBR) value], blood pressure, intraocular pressure (IOP), blood glucose, blood insulin and plasma ET-1 were determined before and every hour up to 3 h after an oral intake of 75 g of glucose.


RESULTS
The SBR increased in the normal glucose tolerance group at all times during the GTT, but it decreased significantly in the abnormal glucose tolerance group (P < 0.05). Before the GTT, the plasma ET-1 level was not significantly different in the two groups; however, the level increased 1 h after the oral GTT in the abnormal glucose tolerance group (P < 0.05). No significant changes were observed in mean blood pressure or IOP.


CONCLUSIONS
ONH circulation increased after glucose intake in the normal glucose tolerance group and remained high even after the blood glucose level had returned to its baseline. The decrease in ONH circulation in the abnormal glucose tolerance group was attributed partly to the increased ET-1.
Kida
Teruyo
T
Department of Ophthalmology, Osaka Medical College, Osaka, Japan. kidateruyo@yahoo.com
Sugiyama
Tetsuya
T
Oku
Hidehiro
H
Harino
Seiyo
S
Ikeda
Tsunehiko
T
D000328:Adult; D001775:Blood Circulation / Q000502:physiology; D001783:Blood Flow Velocity / Q000502:physiology; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure / Q000502:physiology; D019332:Endothelin-1 / Q000097:blood*; D005260:Female; D005951:Glucose Tolerance Test; D006442:Glycated Hemoglobin / Q000032:analysis; D006801:Humans; D006943:Hyperglycemia / Q000503:physiopathology*; D007328:Insulin / Q000097:blood; D007429:Intraocular Pressure / Q000502:physiology; D017078:Laser-Doppler Flowmetry; D008297:Male; D008875:Middle Aged; D009898:Optic Disk / Q000098:blood supply*; D012039:Regional Blood Flow / Q000502:physiology
D001786:Blood Glucose; D019332:Endothelin-1; D006442:Glycated Hemoglobin; D007328:Insulin