RESUMO
The inability to augment capillary blood volume (CBV) in response to insulin or glucose is thought to contribute to insulin resistance (IR) by limiting glucose uptake in key storage sites. Understanding the mechanisms that contribute to impaired CBV augmentation early in the onset of IR may lead to new future therapies. We hypothesized that inactivity alters the balance of vasoactive eicosanoids and contributes to microvascular IR. In ten activity-restricted (AR) and six normal activity adult male rhesus macaques, contrast-enhanced ultrasound of skeletal muscle blood flow and CBV was performed at baseline and during intravenous glucose tolerance test (IVGTT). Plasma was analyzed for vasoconstrictor hydroxyeicosatetraenoic acids (HETEs) and the ratio of vasodilatory epoxyeicosatrienoic acids (EETs) to their less biologically active dihydroxyeicosatrienoic acids (DHETs) as an indirect measure of soluble epoxide hydrolase activity. AR primates were IR during IVGTT and had a 45% lower glucose-stimulated CBV response. Vasoconstrictor 18-HETE and 19-HETE and the DHET/EET ratio were markedly elevated in the AR group and correlated inversely with the CBV response. In addition, levels of 18-HETE and 19-HETE correlated directly with microvascular IR. We conclude that a shift toward increased eicosanoid vasoconstrictor tone correlates with abnormal skeletal muscle vascular recruitment and may contribute to IR.
Assuntos
Ácidos Hidroxieicosatetraenoicos/farmacologia , Resistência à Insulina/fisiologia , Microcirculação/efeitos dos fármacos , Músculo Esquelético/irrigação sanguínea , Vasoconstrição/efeitos dos fármacos , Vasoconstritores/farmacologia , Animais , Volume Sanguíneo/efeitos dos fármacos , Capilares/efeitos dos fármacos , Sistema Enzimático do Citocromo P-450/metabolismo , Modelos Animais de Doenças , Teste de Tolerância a Glucose , Macaca mulatta , Masculino , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismo , Fluxo Sanguíneo Regional/efeitos dos fármacosRESUMO
This paper presents a method for calibrating slab coupled optical fiber sensors (SCOS). An automated system is presented for selecting the optimal laser wavelength for use in SCOS interrogation. The wavelength calibration technique uses a computer sound card for both the creation of the applied electric field and the signal detection. The method used to determine the ratio between the measured SCOS signal and the applied electric field is also described along with a demonstration of the calibrated SCOS involving measuring the dielectric breakdown of air.