摘要:

Effective capillary flow and total coronary blood flow to the myneardium were studied in closed chest anesthetized dogs using a coincidence counting system and a bolus injection of rubidium-84. Effective capillary flow was calculated as the relation of myocardial uptake of the tracer, counted externally, to the integrated arterial concentration curve, obtained by continuous counting of arterial radioactivity in a well counter, and extrapolating the downslope of the first circulation. Total coronary blood flow was determined from the Fick principle by dividing the integrated difference of arterial and coronary sinus rubidium-84 concentrations into the myocardial uptake. The studies were repeated after intravenous administration of isoproterenol, norepinephrine and nicoline in three groups of dogs, each animal serving as its own control. During infusion of norepinephrine and after injection of nicotine, a relatively greater increase in total coronary flow as compared to effective capillary flow was observed, whereas isoproterenol effected a nearly proportional increase in both. The physiological basis of the method is discussed and interpretation of the data offered. It is suggested that the action of these agents may be mediated through different effects on the adrenergic receptors of the heart.

ISSN:0002-9629    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

In order to explore the relationship between adenosine triphosphate (ATP) and the electrocardiograph (ECG), isolated rat hearts were perfused at a constant pressure with 2,4-dinitrophenol (DNP) or with anoxic solutions. Another group of hearts was perfused with oxygenated solution, but at reduced perfusion rates and pressures. Oxygen consumption increased in DNP experiments and decreased in low flow experiments. Coronary flow increased and left ventricular systolic pressure did not change significantly in anoxia and DNP experiments, whereas coronary flow and left ventricular systolic pressure fell in low flow experiments. Cardiac rate fell in all groups of experiments. Although creatine phosphate and ATP fell markedly in anoxia and DNP experiments ST segment alterations were delayed and could be normal with profound high energy reduction. In low flow experiments there was no significant reduction in ATP, yet ST alterations in the ECG occurred early. It is concluded that although ATP may ultimately furnish the energy for ion transport and maintenance of the normal ECG, other factors that affect depolarization and repolarization are more important in determining the response of the electrocardiogram to acute hypoxia.

ISSN:0002-9629    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

Changes in myocardial blood flow as measured with the Nenon-133 precordial clearance method were studied following selective coronary artery injection of Na-methylglucamine diatrizoate (Hypaque-M 75%). Measurements started 15 to 25 seconds after injection of the radiopaque agent showed a substantial decrease in flow in one dog. no difference in two dogs and large increases in two dogs as compared to control measurements made after coronary injections of saline. Flow measurements started between 27 and 50 seconds showed increases after nine injections in eight dogs averaging 23% greater than control values (p<.01). Measurements started 60 to 75 seconds after diatrizoate in three dogs revealed increases of 12 and 19% in two and no difference from control in one. Flow measurements started 25 to 40 seconds after diatrizoate in these same three dogs showed increases of 51, 35 and 10%, respectively. Cardiac outputs determined 30 to 90 seconds following 14 diatrizoate injections in ten dogs showed variable changes which could not be related to the time of measurement. Sinus bradyeardia and a fall in the arterial blood pressure occurred after all diatrizoate injections. The changes in heart rate and blood pressure were maximal at five to tea seconds and gradually returned to preinjection levels within 60 seconds.

ISSN:0002-9629    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

The uptake of C14-L-valine by the jejunal mucosa obtained by peroral biopsy was determined in 15 normal and ten obese subjects. The kinetics of amino acid uptake were investigated by incubating the intestinal tissue with L-valine in concentrations of 0.5 to 10 mM. The intestinal mucosa of the obese subjects accumulated significantly more valine than the normal at incubation concentration of 2, 6, 8 and 10 mM. Both groups approached saturation at substrate concentrations of 8 to 10 mM. The kinetic constants, Km(the apparent affinity constant for transport), and Vmax(the maximal transport rate) were increased significantly in the obese subjects. The concentration of valine in the intracellular water was approximately 2 to 7 times that of the incubating fluid, indicating uphill transport. The I/O ratio was significantly higher in the obese subjects than in the normal at incubation concentrations of 2, 6, 8 and 10 mM. The DNA content of the intestinal mucosa of two obese subjects was less than normal, suggesting a decrease in cell number and an increase in cell size. It is postulated that the increased intestinal uptake of amino acids in obesity represents primarily an adaptive phenomenon to increased food intake.

ISSN:0002-9629    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

Visceral lesions were produced in mice by normal mode pulsed ruby and neodymium irradiation at energy levels ranging from 4 to 400 joules/cm2and by continuous wave CO2laser irradiation at power levels ranging up to 24 watts. The gross and microscopic changes following laser irradiation resembled basically lesions produced by other heat producing agents, but differed in selectivity for pigments and production of pressure effects. The variations in the lesions of different organs appeared to be due primarily to differences in pigment content, tissue structure and response to injury. The rapid temperature rise during pulsed laser irradiation led to vaporization of tissue fluids causing large intercellular spaces with cellular distortion. The pressure waves produced changes resembling blast injuries. Lesions produced by CO2lasers showed primarily thermal changes. The mechanisms of the interaction between radiation and tissue component were considered in regard to the parameters of the laser output.

ISSN:0002-9629    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

A death certificate analysis of mortality from ischemic heart disease in Icelandic males during 1951 to 1960 revealed a striking urban-rural difference for ages 35 to 64 and even up to 74, while the oldest age groups showed little difference. The crude rates, therefore, did not differ impressively but the rates per 100,000 for ages 35 to 64 were: Reykjavik 175.4; other towns 151.6; combined urban area 166.5; and rural area 78.2. At these ages, accordingly, the urban mortality rate for ischemic heart disease was more than twice as high as the rural rate. The Icelandic diet is traditionally rich in protein and fats and the consumption of animal fats, including dairy fats is, if anything, higher in rural areas than in towns. The caloric intake in relation to expenditure was, however, probably higher in the towns. It is suggested that overnutrition per se may be of greater importance in predisposing to ischemic heart disease than richess of the diet in fats.

ISSN:0002-9629    

出版商:OVID    

年代:1969

数据来源: OVID

摘要:

A 23 year old woman developed a hemorrhagic diathesis, acute renal failure, progressive coma with proteinuria and hypertension in the postpartum period. Light and electron microscopic studies of the renal biopsy specimen disclosed glomerular changes suggestive of pre-eclampsia. Striking intravascular fibrin thrombi and “fibrinoid” were also noted, a finding confirmed by immunofluorescence studies. An immunologic process was suggested by the finding of β, C, IgM and IgG among the glomerular capillary loops, arterial and arteriolar walls. At autopsy, there was disseminated intravascular coagulation. The role of intravascular coagulation in the pathogenesis of this patient's lesions is discussed. The mechanisms involved in the generalized Shwartzman reaction and experimental toxemia of pregnancy may have implications that are relevant to the development of eclampsia in the postpartum period.

ISSN:0002-9629    

出版商:OVID    

年代:1969

数据来源: OVID

ISSN:0002-9629    

出版商:OVID    

年代:1969

数据来源: OVID