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INSULIN‐INDUCED AUGMENTATION OF CREMASTER MUSCLE INTRACAPILLARY BLOOD VOLUME IS IMPAIRED IN DB/DB MICE
Author(s) -
VanTeeffelen Jurgen Willem,
Vink Hans,
Eskens Bart
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.924.13
Subject(s) - glycocalyx , insulin , intravital microscopy , cremaster muscle , blood volume , medicine , microcirculation , hemodynamics , endocrinology , hematocrit , chemistry , skeletal muscle , anatomy , biochemistry
Insulin sensitivity has been related to insulin's ability to increase capillary blood volume in skeletal muscle. Based on our previous studies indicating that agonists augment intracapillary blood volume by increasing blood access into the endothelial glycocalyx, we hypothesize that insulin increases blood volume within individual capillaries in muscle of healthy mice, but not of diabetic mice with manifested glycocalyx damage. Intravital microscopy of cremaster muscle was performed in anesthetized C57Bl/6 (CON, n=5) and db/db mice (DB, n=5). Capillary hemodynamics (red blood cell flux & velocity, anatomic diameter) were monitored at baseline and during insulin administration to the superfusate (20 – 200 μU/ml). Capillary tube hematocrit (Hcap) was calculated as measure of functionally perfused capillary blood volume. In CON, Hcap was 0.093 ± 0.008 (SEM, n=25 capillaries) at baseline; insulin increased (P<0.05) Hcap to 0.143 ± 0.011 (20 μU/ml) and 0.0139 ± 0.008 (200 μU/ml). In DB, baseline Hcap was already elevated (0.154 ± 0.01, n=36 capillaries); insulin administration resulted in stagnant RBCs in 44% of the examined capillaries while in the remaining Hcap did not change. Our results indicate that the insulin‐induced increase of capillary blood volume in muscle involves a glycocalyx‐dependent volume increase in individual capillaries rather than recruitment of additional capillaries.