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Relationships between microvascular function and capillary structure in diabetic and nondiabetic human skin
M A Katz1, P McCuskey, J L Beggs
1Research Service, Veterans Administration Medical Center, Tucson, AZ 85723.
Diabetes
|October 1, 1989
Summary
Diabetic microvascular dysfunction is not strongly linked to capillary structure changes. Permeability-surface area product (PS) increases with capillary density, but basement membrane thickness shows no correlation.
Area of Science:
- Vascular Biology
- Diabetic Complications
- Microcirculation Physiology
Background:
- Diabetic microvascular complications, particularly ischemia, are often attributed to capillary abnormalities like basement membrane thickening.
- Previous research indicated differing postarteriolar flow responses in diabetic versus non-diabetic subjects after exercise, with higher resting permeability-surface area product (PS) in diabetics.
Purpose of the Study:
- To investigate the correlation between morphometric capillary variables and hemodynamic/physiological measurements in type II diabetic subjects.
- To determine if capillary basement membrane thickness or other structural changes explain altered microvascular function in diabetes.
Main Methods:
- Forearm skin biopsies from diabetic and non-diabetic subjects were analyzed using electron microscopy for capillary radius, basement membrane thickness, endothelial cell density, and luminal membrane folding.
- Morphological data were correlated with previously measured physiological variables (e.g., resting permeability-surface area product) using stepwise analysis of covariance.
Main Results:
- Correlations between morphological variables and physiological results were sparse, with capillary basement membrane thickness showing no significant association.
- The highest correlation (r2=.432) was between resting permeability-surface area product (PS) and the ratio of capillary density to endothelial cell number per capillary.
- Increased PS in diabetic subjects was observed independently of capillary density levels.
Conclusions:
- Diabetic microvascular physiological variables show limited direct correlation with most morphometric capillary changes.
- Minor permeability alterations correlate with capillary density and endothelial cell number, but do not fully explain the increased PS in diabetes.
- The study suggests that increased microvascular permeability in diabetes may be a primary change, not solely a consequence of structural alterations.