摘要:

Oxidative and phosphorylative activities were measured polarographically in mitochondria isolated from the right and left ventricles of normal and chronically stressed dog hearts. Chronic myocardial stress was produced experimentally by surgical procedures (combined tricuspid insufficiency and pulmonary stenosis, pulmonary insufficiency, aortic stenosis, aortic insufficiency, Potts's anastomosis) and by inducing thyrotoxicosis. Experimental stress periods ranged from 332 to 608 days. Some of the dogs had overt symptoms of congestive heart failure at the time they were killed.Mitochondria isolated from the stressed hearts had abnormally high values for oxidative activity and respiratory control ratios when incubated in the presence of malate-pyruvate. In the presence of succinate, they had either normal or slightly elevated values for oxidative activity and respiratory control ratios. No differences were found between mitochondria from normal and stressed hearts with regard to the efficiency (ADP/O) of oxidative phosphorylation. Estimates of mitochondrial protein per gram of myocardial tissue indicated that the stressed hearts contained normal amounts of mitochondria. The results of this study suggest that the mitochondrial oxidative and phosphorylative capabilities of the chronically stressed myocardium are not impaired.

ISSN:0009-7330    

出版商:OVID    

年代:1968

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1968

数据来源: OVID

摘要:

The dynamic changes in the coronary circulation and the response to drugs were studied following experimentally induced coronary insufficiency. Flow measurements were made in the left circumflex and descending branches of the coronary artery, and in the ascending aorta; pressures were measured in the ascending aorta and the left ventricle. As the left circumflex coronary artery branch was gradually constricted, reactive hyperemia following a 10-second occlusion of that vessel decreased. When the Degrees of constriction became such that the control resting flow began to fall, there was no reactive hyperemia, and the contractility index of the heart decreased. Within less than 24 hours, flow in the descending branch of the left coronary artery rose, and the cardiac contractility index returned to control; peak flow rate in the descending branch during reactive hyperemia after a 10-second occlusion also increased. The response to isoproterenol, nitroglycerin, and dipyridamole was similar in direction before and after the partial reduction of flow in the left circumflex coronary artery branch. The response was less in the coronary vessel with partial occlusion; in the unimpeded descending coronary artery branch, the response increased progressively. These results are consistent with the development of collateral vessels.

ISSN:0009-7330    

出版商:OVID    

年代:1968

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1968

数据来源: OVID

摘要:

Dynamic elastic moduli (Edyn) and viscous moduli (ηω) of the arterial wall were obtained at a number of sites of the systemic vascular tree of living dogs anesthetized with pentobarbital. Constants were calculated using the first harmonics of pressure and diameter obtained from a Fourier analysis of simultaneously recorded pulse waves. The means and standard errors of Edyn, in dynes cm-2× 106, obtained at mean blood pressures ranging from 87 to 130 mm Hg and pulse frequencies from 1.1 to 2.8 cps were: 3.0±0.33 (9 midthoracic aortas), 9.8±1.2 (7 midabdominal aortas), 11.0 (4 iliac arteries), and 12.3±1.2 (11 femoral arteries). The viscous modulus was approximately 9% of Edynin the midthoracic aorta and approximately 12% of Edynin the abdominal and femoral arteries. Pulse wave velocities calculated from values of Edynand relative wall thickness by the Moens-Korteweg equation agreed with accepted values. A Fourier analysis of pressure and diameter waves was shown to be unsatisfactory for determining the frequency dependence of viscoelastic constants because of anomalous behavior of the viscoelastic parameters. In the midthoracic aorta this behavior may have been partly attributable to artefact; however, there was strong evidence that elsewhere nonlinear pressure and diameter relationships interfered with the accurate determination of the relatively small, higher-order harmonic components.

ISSN:0009-7330    

出版商:OVID    

年代:1968

数据来源: OVID

摘要:

Cardiac hypertrophy was induced in rats by constriction of the aortic arch. Hearts from rats with aortic constriction increased in weight about 50% above those of control rats by 7 days after operation. RNA concentration increased between 24 and 48 hours after constriction and, thereafter, returned toward the control level. DNA concentration of hearts from rats with aortic constriction remained unchanged from that of sham-operated rats. Labeling of heart RNA with32P was increased relative to that of sham-operated rats within the first 4 hours after aortic constriction. However, RNA labeling, relative to the labeling of AMP derived from ATP, increased above that of sham-operated rats only after 4 hours of aortic constriction and rose to maximum or near maximum values by 8 hours after operation.Various methods of extraction of RNA showed that the increase in labeling involved all the major species of RNA (28S, 18S, and 4S), and no evidence was found for the selective stimulation of a minority species. The nucleotide base composition of the various species of heart RNA of rats with aortic constriction was not significantly different from that of normal rats during the 4- to 8-hour period after operation. There was no terminal labeling of sRNA in hearts of either normal animals or those with aortic constriction.

ISSN:0009-7330    

出版商:OVID    

年代:1968

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1968

数据来源: OVID

摘要:

The sequence of events which lead to increased RNA synthesis in the heart following aortic constriction was studied with the use of inhibitors of protein and RNA synthesis. Puromycin given during the first 4 hours after operation inhibited the increase in RNA labeling with [32P] H3PO4that occurred after 4 hours of aortic constriction without inhibiting RNA labeling in sham-operated rats. Puromycin had no effect on the32P labeling of the alpha-phosphate of AMP which suggests that the effect on labeling of RNA is not mediated by the lowering of precursor specific activity. The dose of puromycin used inhibited the labeling of heart muscle protein with3H leucine. Parafluorophenylalanine had no selective inhibitory effect on the increase of RNA labeling in the hypertrophying heart.The most likely interpretation of these data is that, following aortic constriction, synthesis of protein is required for subsequent stimulation of RNA synthesis, and this protein may be dependent upon the synthesis of new RNA templates. Any early increased synthesis would be of a minority species of protein since there was no increase in amino acid labeling of total heart protein until 4 to 6 hours after aortic constriction.The stimulation of RNA labeling by aortic constriction was unaffected by digitalis treatment. The pressure-time index did not correlate with the increased labeling of RNA.

ISSN:0009-7330    

出版商:OVID    

年代:1968

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1968

数据来源: OVID

摘要:

Established pulmonary hypertension associated with hypoxemia in patients with chronic bronchitis is probably secondary to hyperplasia of the smooth muscle of pulmonary arterioles. To investigate the possibility that this increase in pulmonary arterial pressure was reversible, the floating catheter technique was used to study the effects of continuous administration of oxygen for 4 to 8 weeks on the pulmonary circulation.In six patients, there was a gradual fall in pulmonary arterial pressure, the mean pressure for the group being 42.5 mm Hg before, and 32.3 mm Hg after, the period of oxygen administration. All measurements were made when the patients breathed air. There was no change in cardiac output. Hematocrit decreased from 51.4% to 42.5%, but total blood volume remained unchanged.It has been shown previously that brief inhalation of oxygen can cause a slight temporary reduction in the pulmonary hypertension associated with chronic bronchitis and anoxemia. The present findings show that the residual, established hypertension is also reversible if oxygen therapy is continued for weeks. It is suggested that this reversal may be brought about by regression of the muscular hyperplasia of the small pulmonary vessels consequent to longterm relief of hypoxia.

ISSN:0009-7330    

出版商:OVID    

年代:1968

数据来源: OVID