Regional haemodynamic effects of recombinant murine or human leptin in conscious rats.
(41/863)
Regional haemodynamic responses to recombinant murine or human leptin were assessed in conscious, chronically-instrumented, male, Long-Evans rats (350 - 450 g). Human, but not murine, leptin caused a slight hindquarters vasoconstriction, but neither peptide had any effect on mean arterial blood pressure or heart rate. In the presence of the beta(2)-adrenoceptor antagonist, ICI 118551, a hindquarters vasoconstrictor response to human leptin was not seen, and there was a tachycardia, as there was to murine leptin. The nitric oxide synthase inhibitor, N(G)-nitro-L-arginine methyl ester, (L-NAME), did not influence the cardiovascular effects of murine or human leptin. The results indicate that the previously reported sympathoexcitatory effects of murine leptin in anaesthetized rats are not manifest as regional haemodynamic changes in conscious rats, and this is not due to beta(2)-adrenoceptor-mediated vasodilator mechanisms opposing any vasoconstrictor responses. Moreover, the ability of L-NAME to unmask a pressor effect of murine leptin in anaesthetized rats may not be apparent in the conscious state. (+info)
Prevention of hypoxia-induced pulmonary hypertension by enhancement of endogenous heme oxygenase-1 in the rat.
(42/863)
We investigated the role of heme oxygenase (HO)-1 in the development of hypoxia-induced pulmonary hypertension. HO catalyzes the breakdown of heme to the antioxidant bilirubin and the vasodilator carbon monoxide. Hypoxia is a potent but transient inducer of HO-1 in vascular smooth muscle cells in vitro and in the lung in vivo. By using agonists of HO-1, we sustained a high expression of HO-1 in the lungs of rats for 1 week. We report that this in vivo enhancement of HO-1 in the lung prevented the development of hypoxic pulmonary hypertension and inhibited the structural remodeling of the pulmonary vessels. The mechanism(s) underlying this effect may involve a direct vasodilating and antiproliferative action of endogenous carbon monoxide, as well as an indirect effect of carbon monoxide on the production of vasoconstrictors. These results provide evidence that enhancement of endogenous adaptive responses may be used to prevent hypoxia-induced pulmonary hypertension. (+info)
Immunoradiometric assay of circulating C-reactive protein: age-related values in the adult general population.
(43/863)
BACKGROUND: : Increased values of C-reactive protein (CRP), the classical acute phase protein, within the range below 5 mg/L, previously considered to be within the reference interval, are strongly associated with increased risk of atherothrombotic events, and are clinically significant in osteoarthritis and neonatal infection. METHODS: : A robust new polyclonal-monoclonal solid- phase IRMA for CRP was developed, with a range of 0.05-10.0 mg/L. RESULTS: : Plasma CRP values in general adult populations from Augsburg, Germany (2291 males and 2203 females; ages, 25-74 years) and Glasgow, Scotland (604 males and 650 females; ages, 25-64 years) were very similar. The median CRP approximately doubled with age, from approximately 1 mg/L in the youngest decade to approximately 2 mg/L in the oldest, and tended to be higher in females. CONCLUSION: : This extensive data set, the largest such study of CRP, provides valuable reference information for future clinical and epidemiological investigations. (+info)
Effects of three-day bed rest on metabolic, hormonal and circulatory responses to an oral glucose load in endurance or strength trained athletes and untrained subjects.
(44/863)
The study was designed to find out (1) whether the effect of 3-day bed rest on blood glucose (BG) and plasma insulin (IRI) responses to glucose ingestion depends on preceding physical activity and (2) whether plasma adrenaline (A), noradrenaline (NA) and cardiovascular changes following a glucose load are modified by bed rest. Eleven sedentary students (22.5+/-0.3 yrs), 8 long distance runners (18.6+/-0.3 yrs) and 10 strength trained athletes (21.2+/-2.1 yrs) were examined before and after bed rest. Plasma IRI, BG, NA, A, heart rate (HR), and blood pressure (BP) were measured during 2 hrs following glucose (75 g) ingestion. The responses of BG and IRI to glucose load were calculated as incremental areas under the curves (auc). Both in athletes and untrained subjects bed rest markedly increased IRIauc, while BGauc was elevated only in sedentary subjects (p<0.05). The greatest increases in IRIauc and IRI/BG ratios were found in the endurance athletes. The data from all subjects (n = 29) revealed that the initial plasma NA and glucose-induced increases in NA and A were lowered after bed rest (p < 0.01). These effects were most pronounced in the endurance athletes. Bed rest did not influence HR or BP in any group. It is concluded that (1) the athletes have more adequate compensation for the bed-rest-induced decrement in insulin sensitivity than sedentary men; (2) three-day bed rest diminishes basal sympathetic activity and attenuates sympathoadrenal response to oral glucose; (3) endurance athletes have greater sympathetic inhibition than strength athletes or sedentary men. (+info)
Circulatory impairment induced by exercise in the lizard Iguana iguana.
(45/863)
Mechanical integration of the cardiac, muscular and ventilatory pumps enables mammals to vary cardiac output over a wide range to match metabolic demands. We have found this integration lacking in a lizard (Iguana iguana) that differs from mammals because blood flow from the caudal body and ventilation are maximal after, rather than during, exercise. Because Iguana iguana are constrained from ventilation during intense locomotion, they appear to be unable to recruit the abdomen and thorax as a pump for venous return. This constraint on simultaneous running and costal breathing arises from their musculoskeletal design, which is similar to that of basal tetrapods, and so a constraint on venous return during exercise may be ancestral for tetrapods. We suggest that mechanical coupling of the pulmonary and cardiac pumps may have been important for the evolution of high-speed locomotor stamina in terrestrial vertebrates. (+info)
Pulmonary responses of unilateral positive end expiratory pressure (PEEP) on experimental fat embolism.
(46/863)
The role of positive end expiratory pressure (PEEP) was evaluated in preventing the deleterious mechanical respiratory effects of fatty acid pulmonary embolism. One group of animals had ventilation without PEEP, while the second group had PEEP of 10 cm H2O applied only to the right lung. In the right lung, PEEP slightly reduced the blood flow, increased the vascular resistance, but reduced intersititial edema and reduced the degree of shunting to almost normal. Hypoxemia was prevented in the right pulmonary venous system, but was prominent in the left. The hypoxemia and shunting in the left lung were comparable to the Group I animals without PEEP to either lung. These studies confirm the value of PEEP in the therapy of the pulmonary manifestations of fat embolism which are the lethal factors in the fatty embolism syndrome. (+info)
Vascularization of normal and neoplastic tissues grafted to the chick chorioallantois. Role of host and preexisting graft blood vessels.
(47/863)
Adult, embryonic, and tumor tissues were grafted to the chorioallantoic membrane of the chick embryo to determine whether blood vessels originally within implants were reused in the establishment of a new blood supply. Grafts were examined daily by in vivo stereomicroscopy and in histologic sections. Colloidal carbon injections into the host vasculature served to confirm the precise onset of graft circulation; Preexisting tumor blood vessels disintegrated by 24 hours after implantation and revascularization occurred at 3 days by penetration of proliferating host vessels into the tumor tissue. Adult tissues did not revascularize, and the original graft vasculature progressively disintegrated during the 9 days of observation, Most embryonic tissues revascularized in 1 or 2 days by reperfusion of the existing graft vasculature. Anastomosis of host and graft blood vessels seemed to result from connections between newly formed vascular sprouts arising from both vasculatures. This study indicates that only tumor grafts acquire their blood supply solely by formation of new blood vessels from the host microvasculature. By contrast revascularization of normal tissues, when it does occur, is predominately the result of perfusion of the preexisting graft blood vessels. (+info)
Cardiovascular effects of an intravenous bolus of morphine in the ventilated preterm infant.
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AIM: To examine the cardiovascular effects of an intravenous bolus of morphine, 100 microg/kg, in 17 ventilated preterm infants. METHODS: Heart rate and blood pressure were monitored. Right ventricular output, superior vena caval flow, and the width of the ductus arteriosus were measured by Doppler echocardiography 10 and 60 minutes after the morphine injection, and the values compared with baseline values by the paired t test. RESULTS: There was a small but significant fall in heart rate (2.1% at 10 minutes, 4.3% at 60 minutes) consistent with a sedative effect. There was no effect on systolic, diastolic, or mean blood pressure. There was no significant effect on systemic blood flow as measured by either right ventricular output or superior vena caval flow. Ductal width was significantly reduced by a mean of 16% at 60 minutes, suggesting that normal duct closure was not inhibited. CONCLUSION: No cardiovascular effects of an intravenous bolus of morphine could be detected. (+info)