Impact of increased intramuscular perfusion heterogeneity on skeletal muscle microvascular hematocrit in the metabolic syndrome.
OBJECTIVE
To determine HMV and PS in skeletal muscle of OZR and evaluate the impact of increased microvascular perfusion heterogeneity on mass transport/exchange.


METHODS
The in situ gastrocnemius muscle from OZR and LZR was examined under control conditions and following pretreatment with TEMPOL (antioxidant)/SQ-29548 (PGH2 /TxA2 receptor antagonist), phentolamine (adrenergic antagonist), or all agents combined. A spike input of a labeled blood tracer cocktail was injected into the perfusing artery. Tracer washout was analyzed using models for HMV and PS. HT was determined in in situ cremaster muscle of OZR and LZR using videomicroscopy.


RESULTS
HMV was decreased in OZR versus LZR. While TEMPOL/SQ-29548 or phentolamine had minor effects, treatment with all three agents improved HMV in OZR. HT was not different between strains, although variability was increased in OZR, and normalized following treatment with all three agents. PS was reduced in OZR and was not impacted by intervention.


CONCLUSIONS
Increased microvascular perfusion heterogeneity in OZR reduces HMV in muscle vascular networks and increases its variability, potentially contributing to premature muscle fatigue. While targeted interventions can ameliorate this, the reduced microvascular surface area is not acutely reversible.
Center for Cardiovascular and Respiratory Sciences, West Virginia University Health Sciences Center, Morgantown, West Virginia, USA; Department of Physiology and Pharmacology, West Virginia University Health Sciences Center, Morgantown, West Virginia, USA.
Joshua T
JT
Butcher
Shyla C
SC
Stanley
Steven D
SD
Brooks
Paul D
PD
Chantler
Fan
F
Wu
Jefferson C
JC
Frisbee
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D019086:Bridged Bicyclo Compounds, Heterocyclic; D003497:Cyclic N-Oxides / Q000494:pharmacology; D005231:Fatty Acids, Unsaturated; D006400:Hematocrit; D006834:Hydrazines / Q000494:pharmacology; D024821:Metabolic Syndrome / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D008833:Microcirculation; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D051381:Rats; D044244:Receptors, Thromboxane A2, Prostaglandin H2 / Q000037:antagonists & inhibitors; D013113:Spin Labels
D000975:Antioxidants; D019086:Bridged Bicyclo Compounds, Heterocyclic; D003497:Cyclic N-Oxides; D005231:Fatty Acids, Unsaturated; D006834:Hydrazines; D044244:Receptors, Thromboxane A2, Prostaglandin H2; D013113:Spin Labels; C045749:SQ 29548; C001803:tempol
microcirculation; microvascular hemodynamics; peripheral vascular disease; regulation of skeletal muscle blood flow; rodent models of metabolic syndrome