Response of retinal arteriole diameter to increased blood pressure during acute hyperglycaemia.
OBJECTIVE
To study retinal response in terms of arteriole diameter and retinal thickness secondary to an increase in arterial blood pressure during acute hyperglycaemia.


METHODS
In a randomized, double-blinded, cross-over study, nine healthy persons were subjected to clamping of blood glucose to either 5 mmol/l or 15 mmol/l using somatostatin to control endogenous insulin secretion. The response of retinal arterioles in terms of diameter as determined with the retinal vessel analyser (RVA) and retinal thickness as assessed by optical coherence tomography (OCT) were measured after an increase in arterial blood pressure induced by isometric exercise. Arterial feeding pressure in the eye was assessed from the ophthalmic artery pressure and pulse amplitude measured by ophthalmodynamometry.


RESULTS
Isometric exercise induced a significant increase in mean arterial blood pressure and a significant contraction of the retinal arterioles. An acute increase in blood glucose from 5 mmol/l to 15 mmol/l did not affect either the diameter of retinal vessels or retinal thickness.


CONCLUSIONS
Acute hyperglycaemia per se does not change isometric exercise-induced retinal arteriolar contraction. Metabolic factors other than blood glucose are suspected to be involved in the impairment of retinal autoregulation as seen in hyperglycaemia induced by oral glucose intake.
Jeppesen
Peter
P
Department of Ophthalmology, Aarhus University Hospital, Aarhus, Denmark. pj@dadlnet.dk
Knudsen
Søren T
ST
Poulsen
Per L
PL
Mogensen
Carl E
CE
Schmitz
Ole
O
Bek
Toke
T
D000208:Acute Disease; D000328:Adult; D001160:Arterioles / Q000502:physiology; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure / Q000502:physiology*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology; D006801:Humans; D006943:Hyperglycemia / Q000503:physiopathology*; D008297:Male; D009131:Muscle, Smooth, Vascular; D009880:Ophthalmic Artery / Q000502:physiology; D009884:Ophthalmodynamometry; D012161:Retinal Artery / Q000502:physiology*; D013004:Somatostatin / Q000008:administration & dosage; D041623:Tomography, Optical Coherence; D014661:Vasoconstriction / Q000502:physiology
D001786:Blood Glucose; D013004:Somatostatin