摘要:

We investigated the effect of acute renal vein and hepatic vein hypertension induced by partial balloon-occlusion of the abdominal inferior vena cava (ATVC-O) and the thoracic inferior vena cava (TTVC-O) on systemic and renal hemodynamics and renal function in 13 dogs anesthetized with pentobarbital. When a renal vein pressure of 13 cm H2O was induced by AIVC-O, cardiac output, stroke volume, central venous pressure, renal blood flow, and renal function (GFR, free water clearance, osmolar clearance, urine output, urinary sodium excretion, fractional sodium excretion) decreased significantly. When systemic hemodynamics were restored to control values by transfusion of autolo-gous blood (mean of 9 ml/kg body weight) while renal vein pressure was kept elevated, renal function also was restored. A hepatic venous pressure of 13 cm H2O then was induced by TTVC-O. The effects on systemic hemodynamics and renal function were very similar to those observed during AIVC-O. When systemic hemodynamics were restored to control values by transfusion (mean of 9 ml/kg), while hepatic venous hypertension was maintained by TIVC-O, renal function also was restored. Despite significant changes in natriuresis and diuresis, intrarenal blood flow distribution, as determined by the radioactive microsphere technique, remained essentially unchanged throughout. We conclude that renal and hepatic congestion induced by partial AIVC-O and TTVC-O do not, per se, alter renal function significantly.Circ Res 47: 883-890, 1980

ISSN:0009-7330    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

We studied the reflex control of blood pressure, heart rate, and hindlimb vascular resistance by the carotid sinus baroreceptors in normal (N), experimental renal hypertensive (RH, one kidney renal wrap model), and medial sclerotic (MS) rabbits under urethane anaesthesia using an isolated perfused carotid sinus preparation and auto-perfused hindlimb. The contralateral carotid sinus was denervated. Compared to N rabbits, the blood pressure and hindlimb vascular resistance of RH and MS rabbits were significantly elevated at all carotid sinus pressures 15 weeks after inducing the disease process. The maximum gains of the curves relating carotid sinus pressure to vascular resistance were significantly elevated in the MS and RH rabbits, but those relating carotid sinus pressure to heart rate were significantly reduced. The changes were greatest in the RH group in which the responses also were set to a higher carotid sinus pressure. In the three groups, division of the aortic nerves produced different changes in the sigmoid curves relating carotid sinus pressure to heart rate, blood pressure, and vascular resistance. There was a linear relationship between blood pressure and basal vascular resistance (correlation coefficient 0.88).Circ Res 47: 890-901, 1980

ISSN:0009-7330    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

In this study we measured high fidelity pulsatile pressure and flow waveforms at the inlet to the pulmonary vascular bed to assess the differences in adaptation to acute and chronic pulmonary venous hypertension in awake dogs. Acute elevations in left atrial pressure (Pia) were effected by inflation of left atrial balloons, while chronic elevations were accomplished by placement of aorta to left atrial shunts. Pulmonary artery hydraulic impedance was calculated and analysis of these data revealed marked differences between the responses to acute and chronic elevations of left atrial pressure. The acutely stressed dogs (n = 12) had significantly decreased pulmonary vascular resistance (when Pla= 16.9 ± 1.0 mm Hg, PVR = 212 ± 57 dynes sec/cm5; when Pla= 28.6 ± 1.4 mm Hg, PVR = 18 ± 115 dynes sec/cm6; control Pi. = 6.1 ± 1.5 mm Hg, and PVR = 355 ± 69 dynes sec/cm5) and normal characteristic impedances (Zo) (210 ± 36, 227 ± 39, 178 ± 14 dynes sec/cm5, respectively), indicating recruitment of arteriolar-capillary perfusion density and no change in proximal pulmonary arterial physical properties. The chronic pulmonary venous hypertension group (n = 11) retained normal PVR (496 ± 30 dynes sec/cm5) but demonstrated a markedly higher characteristic impedance, Zo = 361 ± 11 dynes sec/cm5(P <0.001). This indicated a measurably different and extremely potent effect of chronic venous hypertension on the physical properties of the pulmonary vessels with an apparently increased arterial stiffness correlating with a 4-fold increase in Young's elastic modulus. These changes were not reversed by α-adrenergic blockade or acute lowering of left atrial pressures.Circ Res 47: 902-910, 1980

ISSN:0009-7330    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

To explore the effects of diabetes on myocardial function and metabolism we injected male rats with streptozotocin and studied their hearts 8 weeks later. Blood sugar levels in the treated rats were about 600 mg/100 ml. Body and heart growth rates were diminished. When studied in an isolated working rat heart apparatus using 5.5 mM glucose, hearts of diabetic animals showed dimin-ished cardiac output and stroke work at high filling pressures. There also were significant depressions in peak left ventricular systolic pressure, peak aortic flow rate, maximum negative dP/dt, myocardial oxygen extraction, myocardial lactate production, and effluent lactate: pyruvate ratios. Myocardial glycogen stores, calculated glycogen utilization, and pyruvate production were increased in hearts of diabetics, and myocardial oxygen consumption was the same as in control hearts. The end-diastolic pressure-volume relationship was shifted to the right in hearts of diabetics. Most of the abnormalities observed in hearts of diabetic rats persisted when insulin and 15 mM glucose were included in the perfusion medium. Hearts from young rats or from age-matched food-restricted rats with heart weights similar to those of diabetics did not show depressed function or a pressure-volume shift. Our findings indicate that streptozotocin diabetes in rats results in abnormal myocardial performance. This is not due to restrictions in coronary flow or myocardial oxygenation and is not correctable by the provision of high glucose plus insulin in the perfusion medium.Circ Res 47: 911-921, 1980

ISSN:0009-7330    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Diabetes mellitus is associated frequently with congestive heart failure in humans, even in the absence of associated coronary disease or hypertension. Nevertheless, the effects of the diabetic state on myocardial mechanics have not been studied. Accordingly, diabetes was induced in female Wistar rats by injection of streptozotocin (60 mg/kg). Left ventricular papillary muscles were studied 5,10, and 30 weeks later and compared with controls. Relaxation was delayed significantly and velocity of shortening was depressed at all loads. However, the passive and active force-length curves, as well as the series elastic properties, were not altered. The changes in cardiac performance were found over a range of muscle lengths, stimulus frequencies, and bath concentrations of calcium, glucose, and norepinephrine. The duration of diabetes had no major effect on the mechanical changes observed. The possible influences of drug-induced cardiac toxicity, malnutrition, and altered thyroid hormone levels have been considered; the latter two factors could not be excluded completely from having some influence on the mechanical properties of diabetic cardiac muscle. Evidence is cited showing abnor-malities in calcium uptake by sarcoplasmic reticulum and depressed actomyosin ATPase activity. Thus, a cardiomyopathic state has been produced in the rat consequent to the induction of experimental diabetes mellitus. Various mechanisms for this entity have been suggested.Circ Res 47: 922-933, 1980

ISSN:0009-7330    

出版商:OVID    

年代:1980

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

936-938

ISSN:0009-7330    

出版商:OVID    

年代:1980

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1980

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1980

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1980

数据来源: OVID