RESUMEN
Currently, nonpulsatile selective cerebral perfusion for cerebroprotection against thoracic aortic aneurysm is used in clinical settings. We performed synchrotron radiation microangiography to determine the effects on selective cerebral perfusion modulation by pulsatile flow. We established cerebral perfusion at normothermia and severe hypothermia in anesthetized rats, during which cerebral angiography was performed. NG-nitro-L-arginine-methyl ester hydrochloride (L-NAME) was administered to determine the effect of pulsatile flow with nitric oxide synthesis. In comparison with nonpulsatile flow, the relative diameters of small internal carotid artery were 132.11 ± 5.49% and 114.96 ± 4.60% during pulsatile flow at normothermia and severe hypothermia (p < 0.05). The angiographic scores, an indicator of vessel count, for nonpulsatile and pulsatile flow at normothermia were 0.198 ± 0.013 vs. 0.258 ± 0.010 (p < 0.001) and those at severe hypothermia were 0.158 ± 0.017 vs. 0.214 ± 0.015 (p < 0.01), respectively. In comparison with nonpulsatile flow, the relative internal carotid artery diameters during pulsatile flow with and without L-NAME were 98.50 ± 1.7% vs. 114.96 ± 4.6%, respectively, during severe hypothermia. These results show that pulsatile flow is effective in increasing blood vessel diameter, number of vessels, and perfusion distribution range in the rat model and that it was more effective at normothermia during nitric oxide production.
Asunto(s)
Encéfalo/irrigación sanguínea , Puente Cardiopulmonar/métodos , Arteria Carótida Interna/diagnóstico por imagen , Circulación Cerebrovascular/fisiología , Flujo Pulsátil/fisiología , Animales , Angiografía Cerebral/métodos , Masculino , Microcirculación/fisiología , Perfusión/métodos , Ratas , Ratas WistarRESUMEN
We developed a new circulation-assist device that can generate pulsatile assist flow synchronized with the patient's diastolic phase. The device is composed of a drainage tube, a centrifugal pump, an oxygenator, and a sending tube. A portable magnetic valve device composed of a pulse generator and a tamper, which produces intermittent mechanical compression, is attached to the pillow of the sending tube. Preliminary animal experiments were conducted. No changes in the animals' hemodynamics or any device problems were observed during a preliminary 48-h test run. Significant diastolic augmentation was confirmed. This new device may be useful in treating patients with severe heart failure and could be more useful than using percutaneous cardiopulmonary support (PCPS) alone.
Asunto(s)
Insuficiencia Cardíaca/cirugía , Corazón Auxiliar , Flujo Pulsátil/fisiología , Animales , Velocidad del Flujo Sanguíneo/fisiología , Diástole/fisiología , Diseño de Equipo/instrumentación , Masculino , Modelos Cardiovasculares , ConejosRESUMEN
Liposomes are phospholipid vesicles that can serve as carriers of biologically active agents in vitro and in vivo. Here, we describe the movement of liposomes suspended with blood flowing in capillaries. Liposomes were coated with a polymer to extend their lifespan in rat mesenteric blood vessels and detected by fluorescent staining. Liposome activity was observed by intravital microscopy using a high-speed camera system at 5 and 60 min after liposome administration. Liposome velocity was determined using two-dimensional cross-correlation, and blood flow was measured by high-resolution PIV (particle image velocimetry). The results showed that the motion of polymer-coated liposome followed the phase averaged velocity distribution of heartbeats while flowing with red blood cells in microvessels. Liposome particles tend to move toward the near blood vessel wall in the low velocity of blood flow.
Asunto(s)
Capilares/metabolismo , Eritrocitos/metabolismo , Liposomas/farmacocinética , Animales , Velocidad del Flujo Sanguíneo/fisiología , Capilares/fisiología , Femenino , Hemorreología/instrumentación , Hemorreología/métodos , Liposomas/química , Liposomas/metabolismo , Microscopía Fluorescente , Polímeros/química , Flujo Pulsátil/fisiología , Ratas , Ratas Wistar , Circulación Esplácnica/fisiologíaRESUMEN
Red blood cells (RBC) become deformed while flowing through capillaries. We captured images of blood flow in capillaries and of RBC in the rat mesentery using a high-speed camera at 2000 frames/s and then directly measured and estimated the deformation and velocity of RBC in a non-uniform capillary. The distribution of the capillary diameter was determined by image processing. We applied a deformation index and simple modeling to observe RBC deformation in capillaries. The average capillary diameter was approximately 6.2 microm, and the average velocity of RBC was about 1.85 mm/s. The average deformation index of RBC in the capillary was about 1.55. The present results showed that RBC in capillaries generally assume a specific shape depending on external forces such as the velocity of the blood flow and capillary diameter in vivo.
Asunto(s)
Capilares/fisiología , Deformación Eritrocítica , Eritrocitos/fisiología , Animales , Velocidad del Flujo Sanguíneo , Femenino , Ratas , Ratas Wistar , Circulación EsplácnicaRESUMEN
Carpronium chloride, a hair growth reagent, is known to have a vasodilatory action, but its direct effect on the microcirculation has been known very primitively. This study was aimed to examine its effects on the vascular smooth muscles and blood flow in rat mesenteric arterioles using intravital videomicroscopy. After topically applying carpronium chloride on the microvasculature, we measured changes of diameter and blood flow in the arterioles. During its topical application, arteriolar vasodilation and flow increase were observed, while no change occurred in the mean systemic blood pressure. Our in vivo studies indicated that carpronium chloride achieved dilatation of vascular smooth muscle in the microcirculation.
Asunto(s)
Velocidad del Flujo Sanguíneo/efectos de los fármacos , Microcirculación/efectos de los fármacos , Circulación Esplácnica/efectos de los fármacos , Ácido gamma-Aminobutírico/análogos & derivados , Animales , Arteriolas/efectos de los fármacos , Arteriolas/fisiología , Presión Sanguínea/efectos de los fármacos , Femenino , Masculino , Microcirculación/fisiología , Microscopía por Video , Músculo Liso Vascular/efectos de los fármacos , Músculo Liso Vascular/fisiología , Ratas , Ratas Wistar , Circulación Esplácnica/fisiología , Vasodilatación/efectos de los fármacos , Ácido gamma-Aminobutírico/farmacologíaRESUMEN
A new technique using particle image velocimetry (PIV) has been developed to evaluate the detailed velocity profiles of red cells flowing in microvessels. The microcirculation in rat mesentery was directly observed using high-speed videomicroscopy, and the images of red cells flowing in the mesenteric arterioles were recorded simultaneously with the arterial blood pressure. Based on the high-speed videomicroscopic images obtained, velocity vectors in single or branched arterioles were evaluated to obtain velocity profiles across the cross-section of arterioles. It was shown that in single and straight arterioles the velocity profile was blunt with a pit at the central region, and its pit was marked in bifurcation. The present technique enables us to analyze red cell velocity profiles up to 0.8 microm in the spatial resolution and 1 msec in the time interval.