title: Cold pressor test and plasma endothelin-1 concentration in primary open-angle and capsular glaucoma.
abstract: OBJECTIVE
  The authors investigate cutaneous capillary blood flow using the cold pressor test and plasma endothelin-1 (ET-1) concentration in primary open-angle glaucoma (POAG) and capsular glaucoma (CG), and evaluate the connection between the two factors, which reflect vasoconstrictive mechanisms with a potential role in the pathogenesis of glaucoma.
  
  
  METHODS
  The ET-1 concentration of venous blood plasma samples from 20 patients with POAG, 22 patients with CG, and 44 healthy volunteers was measured using a radioimmunoassay kit. On a separate occasion, the right hand was subjected to the cold pressor test (hand immersed in 4 degrees C water for 30 seconds, then in 30 degrees C water for 2 minutes), during which cutaneous capillary blood flow of the left middle finger was measured using a Periflux 4001 Master Laser Doppler Flowmeter (Perimed AB, Järfälla, Sweden).
  
  
  RESULTS
  In the CG group, baseline cutaneous capillary blood flow was significantly lower than either that of POAG (p = 0.001) or that of the healthy group (p = 0.046). In the CG group, time to maximal cold-induced flow reduction was significantly longer than in the POAG group (p = 0.028) or in the healthy group (p = 0.025). Also, recovery time was significantly longer in CG than in the healthy group (p = 0.008) and tended to be longer than in the POAG group. No statistically significant difference between the groups was found either in the frequency of increased vasospastic response (cold-induced flow reduction higher than 70% of the baseline value) or in ET-1 concentration. No correlation was seen between ET-1 concentration and the findings of the cold pressor test.
  
  
  CONCLUSIONS
  The results suggest that in CG, which is a systemic disease with vascular abnormalities, baseline cutaneous capillary perfusion and its response to cold and warmth are altered, without any alteration of plasma ET-1 level. The authors found that both plasma ET-1 level and the response to the cold pressor test are normal in patients with POAG. These findings suggest that regulation of cutaneous capillary perfusion and the concentration of plasma ET-1 are not related to each other in patients with glaucoma.
authors.affiliation: 1st Department of Ophthalmology, Semmelweis University Medical School, Budapest, Hungary.
authors.forename: G
authors.initials: G
authors.lastname: Holló
authors.forename: P
authors.initials: P
authors.lastname: Lakatos
authors.forename: K
authors.initials: K
authors.lastname: Farkas
mesh_terms: D015415:Biomarkers / Q000097:blood; D001794:Blood Pressure; D002196:Capillaries / Q000502:physiology; D003080:Cold Temperature; D019332:Endothelin-1 / Q000097:blood*; D017889:Exfoliation Syndrome / Q000097:blood* / Q000175:diagnosis / Q000503:physiopathology; D005260:Female; D005500:Follow-Up Studies; D005902:Glaucoma, Open-Angle / Q000097:blood* / Q000175:diagnosis / Q000503:physiopathology; D006801:Humans; D007429:Intraocular Pressure; D017078:Laser-Doppler Flowmetry; D008297:Male; D008875:Middle Aged; D011863:Radioimmunoassay; D012039:Regional Blood Flow; D012867:Skin / Q000098:blood supply*; D014661:Vasoconstriction
chemical_list: D015415:Biomarkers; D019332:Endothelin-1