Myocardial function and coronary blood flow response to acute ischemia in chronic canine diabetes

To examine the influence of preexistent diabetes mellitus on left ventricular performance and coronary blood flow responses to acute ischemia, mild normoglycemic diabetes was induced in nine mongrel dogs after three doses of alloxan, (20 mg/kg, iv), at monthly intervals. Hemodynamic measurements and coronary blood flow (85Kr clearance) were obtained before and after the onset of ischemia. This was produced by occlusion of the proximal left anterior descending coronary artery via a balloon-type catheter in nine intact anesthetized diabetic dogs and 10 nondiabetic dogs. During the 1st hour of ischemia in the diabetic group, the end-diastolic pressure rose from 7 +/- 1.1 (mean +/- SE) mm Hg to 23.8 +/- 2.3 without a significant increase of end-diastolic volume. In controls end-diastolic pressure rose from 8.6 +/- 1.1 mm Hg to 15.3 +/- 1.4, and end-diastolic volume was significantly increased, so that the ratio of end-diastolic pressure and volume was significantly higher in the diabetic group (P less than 0.005). Although indices of contractility did not differ, stroke volume and work reductions were significantly greater in diabetics, despite the fact that coronary blood flow was reduced to a similar extent. Size of the ischemic areas appeared comparable as judged by distribution of dye injected distal to the occlusion. Since potassium loss and sodium gain in the inner and outer layers of ischemic tissue did not differ between the two groups, the intensity of ischemia seemed similar. Glycogenolysis was unimpaired in the diabetic ischemic muscle but triglyceride levels remained elevated. Morphologically the diabetic myocardium was characterized by a diffuse accumulation of periodic acid-Schiff-positive glycoprotein in the interstitium, which was thought to limit diastolic filling of the ischemic ventricle and to contribute to the substantial reduction of ventricular performance.

The role of ethanol in cardiac disease

The widespread use of ethyl alcohol suggests its potential importance in clinical medicine. There is no proven therapeutic effect in cardiac patients and its role as an etiologic factor in heart disease has been disputed over the years and attributed to coexistent malnutrition. The latter factor, however, has been dissociated from ethanol use in many patients with the cardiomyopathic form of heart failure. Major support for the role of ethanol as a toxic agent when used in large amounts for a prolonged period has been obtained in various species of animals, including the subhuman primate. Abnormalities include depression of ventricular function, and metabolic and morphologic changes that parallel the changes in humans with preclinical malfunction of the heart. While the mechanism of progression to heart failure or arrhythmias is not known, several factors may be associated. These include, particularly in males, the cumulative effects of ethanol alone or after intensified drinking episodes, simultaneous exposure to trace metals in excess, and occasional specific nutritional deficiency or superimposed infection. The low prevalence of clinical nutritional deficiency in patients with alcoholic cardiomyopathy and the infrequency of heart disease in patients with cirrhosis or neuropathy supports the view that the cardiac abnormality is commonly not dependent on malnutrition. Clinical data indicate that the cessation of alcohol intake may reverse the disease or interrupt its progression in many patients. However, the pathogenic process may continue unabated in some patients who become abstinent.

The effects of tolbutamide on the myocardium in experimental diabetes

The effects of chronic tolbutamide treatment were examined in a diabetic animal model in which abnormal myocardial function and composition have previously been demonstrated. Eight diabetic dogs were given tolbutamide 250 mg/day orally and compared with seven untreated diabetics, five healthy dogs receiving tolbutamide, and eight normal controls. After one year, resting hemodynamic studies in the intact anesthetized state showed that treated diabetic dogs had a significantly higher left ventricular end-diastolic pressure of 12.1+/-1.3 mm Hg associated with normal end-diastolic volume, compared to 6.1+/-0.8 mm Hg in untreated diabetics (P less than 0.01) and 6.3+/-0.5 in normals. Stroke work and ejection fraction were similar to normals. Acute volume expansion revealed a larger rise of left ventricular end-diastolic pressure in treated and untreated diabetics than normals, without a significant stroke volume response in treated diabetics. Enhanced stiffness of myocardium appeared to be related to interstitial accumulation of periodic acid-Schiff staining material, further intensified in treated diabetics by triglyceride accumulation observed on electron microscopy and by chemical analysis. Thus treatment of diabetes with tolbutamide, despite improved glucose tolerance, effected further reduction of left ventricular function and altered morphology of myocardium.

Diabetes mellitus and left ventricular function

Chronic diabetes mellitus can alter left ventricular function independent of vascular effects. On the basis of available morphologic data in human and canine diabetics, alterations of myocardial interstitium may be the basis for this preclinical abnormality. The abnormal function is independent of apparent duration and treatment by diet, insulin, or hypoglycemic agents. It occurs in both sexes and is independent of age. Whether the observed functional abnormality progresses to clinical heart failure may depend on intensification of the underlying pathophysiology of the myocardium or superimposition of complications such as hypertension, obesity, and obstructive disease of the coronary vessels.

Chronic smoking in an animal model. Effects on clotting and fibrinolysis

The effects of chronic smoking upon fibrinogen turnover and other clotting parameters, were studied prospectively in an animal model maintained on a chronic program for a period of 18 months. The animal received the equivalent on a weight basis of 11/2 packs of cigarettes daily, smoked by a human subject with the weight of 70 kg. The obtained results suggested significant enhancement of the coagulation mechanism in the smoking animals developing over the period of observation particularly when combined with high lipid diet.

Myocardial ischemia and cell acidosis: Modification by alkali and the effects on ventricular function and cation composition

Myocardial cell pH was measured with 5, 5 dimethyl-2, 4-oxazolidinedione (DMO) in intact anesthetized dogs by a transient indicator dilution technique. Bolus injections of labeled DMO, vascular, extracellular and water indicators were made into the left anterior descending coronary artery, and blood samples were collected from the great cardiac vein. The steady state distribution of DMO between cells and plasma was calculated from the mean transit times of the indicator. Normal myocardial cell pH averaged 6.94 and changed by 58% of the concomitant alterations in plasma pH after infusions of acid or alkali. Myocardial ischemia induced by inflation of a balloon tip catheter in the left anterior descending coronary artery resulted in progressive decreases in cell pH to 6.59 by 1 hour. Infusions of sodium carbonate diminished intracellular acidosis. Hemodynamic studies during 4 hours of ischemia with blood pH at 7.55 to 7.60 indicated a significantly reduced left ventricular end-diastolic pressure and increased stroke volume by comparison with findings in animals given infusions of saline solution. Ventriculograms revealed improved wall motion in the ischemic segment after infusion of alkali. Precordial mapping showed a significant reduction in the number of leads with S-T segment elevation as well as in the sum of S-T segment elevations, but R wave amplitudes did not differ from those in control studies. Calculations of extracellular space, tissue water and cation content revealed a reduced gain of cell sodium ion and loss of cell potassium ion during ischemia after alkali treatment. The latter may account for the S-T segment responses, whereas enhanced ventricular performance may be related to reduced competition of hydrogen ion with calcium ion for binding sites on contractile protein.

Cardiovascular effects of long-term cigarette smoking and nicotine administration

The nature of the cardiovascular risk in cigarette smokers has not been characterized. To compare the relative effects of long-term smoking and nicotine administration on the cardiovascular system, 18 month old beagle littermates were prepared with a permanent tracheostomy. They were classified into three groups: I, seven control dogs; II, nine dogs that smoked seven cigarettes/day; and III, eight dogs that received an equivalent amount of nicotine. After a period of up to 22 months, the animals were catheterized under anesthesia for assessment of left ventricular function and volumes by indicator-dilution technique. Heart rate, stroke volume, left ventricular end-diastolic pressure and volume and intraventricular conduction times did not differ significantly in the three groups. Left ventricular ejection fraction was 44 +/- 3 percent (mean +/- standard error of the mean) in the control group, 35 +/- 3 percent in the dogs that smoked cigarettes (P less than 0.05) and 27 +/- 3 percent in those given nicotine (P less than 0.01) despite similar values for end-diastolic variables in the three groups. The first derivative of left ventricular pressure (dP/dt) normalized for pre- and afterload was 2.4 +/- 0.2 cm/sec -1 in the control group, 1.41 +/- 0.12 in the cigarette-smoking group (P less than 0.005) and 1.34 +/-0.08 in the nicotine group (P less than 0.01). Although mean aortic pressure was significantly elevated in both the smoking (127 +/- mm Hg) and nicotine (127 +/- 10 mm Hg) groups, there was no significant correlation with the contractility indexes. Reduction of afterload to normal levels did not affect the abnormal ventricular performance. Hypertrophy, inflammation and abnormalities of cell ultrastructures were not present, and myocardial lipid and cation composition were normal. Since interstitial fibrosis was evident in both experimental groups, an alteration of elastic elements may be operative. These cardiovascular abnormalities appear to be predominantly dependent on the nicotine of cigarettes.

The effect of gibberellic acid alone and when combined with [2-chloroethyl]-trimethyl ammonium chloride on the growth and alkaloid content of Solanum laciniatum aiton

Solanum laciniatum Aiton treated with Gibberellic acid (GA3), [2-chloroethyl]-trimethyl ammonium chloride (CCC), and their combinations at early and late stages of growth showed that early application of 2000 ppm CCC produced the greatest stem, leaves, and whole plant dry weight, followed by the combination of early application of 1000 ppm CCC and late application of 100 ppm GA3; whereas all GA3 treatments decreased the dry weight production compared with the controls. Regarding the glyco-alkaloids, the highest percentage was obtained from the whole plant by early applications of both strengths of GA3 compared with other treatments or the controls. On the other hand, early application of 1000 ppm CCC and also late application of 50 ppm GA3 when combined with early application of either 1000 ppm or 2000 ppm CCC produced greater alkaloid percentage yields in stem, leaves, and whole plants more than other treatments or the controls. However, early application of 2000 ppm CCC produced the highest content of alkaloids in leaves and whole plants; this was followed by yields from early application of 2000 ppm CCC and 50 ppm GA3; yields from early application of 100 ppm GA3 and 1000 ppm CCC; and yields from early application of 1000 ppm CCC +50 ppm GA3.

Effects of some growth hormones on plant vigour and volatile oil of Origanum majorana L

Origanum majorana L. treated with either 50 or 100 mg/l of maleic hydrazide (MH), 2.4-dichlorophenoxy acetic acid (2.4-D), N-dimethylaminosuccinamic acid (B995), [2-chloroethyl]-trimethyl ammonium chloride (CCC), indol-3-yl-acetic acid (IAA) or gibberellic acid (GA3) in the presence or absence of 25 mg/l kinetin, showed that only 100 mg/l GA3 with or without kinetin was able to increase plant height than all other treatments and the controls. On the other hand, both IAA and GA3 concentrations and 2000 mg/l CCC markedly increased the dry weight of the plants in the absence of kinetin, whereas when kinetin was combined, only IAA in both concentrations increased the dry weight of the whole plants. Concerning essential oil %, the highest yields were obtained using 100 mg/l MH, 50 mg/l 2.4-D and 2000 mg/l CCC for leaves and 100 mg/l MH, 1000 mg/l B995 and 50 mg/l 2.4-D for flowers in the absence of kinetin, whereas in the presence of kinetin, the higher yields of essential oil were obtained by using 1000 mg/l B995 and 25 mg/l 2.4-D for flowers and only 50 mg/l 2.4-D for leaves.

The effect of angiotensin on myocardial contractility

Previous studies of the effect of angiotensin on myocardial contractility have yielded conflicting results. Possible reasons for the observed disparities include differences in techniques for measuring contractility, in species (dog, cat, and man), in myocardial state (normal or diseased), in preparation observed (heart-lung, isolated heart, papillary muscle, atrial myocardium, intact heart), and in dosage schedule. Moreover, there are no reported studies in the intact human heart, normal or diseased, in which contractility measurements are based on velocity-force relations. To resolve the conflict, left ventricular myocardial contractility was measured using the same expressions for the force-velocity relationship in all subjects. Studies were performed in five normal human subjects, six patients with cardiomyopathy, eight normal mongrel dogs, and six dogs with ischemic myocardial scarring, before and during angiotensin infusions in dosages producing 15--20-mm Hg increases of aortic diastolic pressure. Contractile element velocity at peak, dP/dt (Vce) and the Frank-Levinson contractility index (CyIx), which normalizes Vce for diastolic fiber length, decreased during angiotensin infusion in all groups. The mean decreases (11 to 19) per cent in Vce, 15 to 23 per cent in CyIx, SEM's 4-5 per cent) were significant (P values ranging from smaller than 0.05 to smaller 0.005) in the normal hearts of dogs and man and in the scarred canine hearts, in which preangiotensin Vce and CyIx were normal. In the cardiomyopathy group, in which contractility was depressed before angiotensin, the drug elicited a further decrease in Vce (mean fall 17 plus or minus 7 per cent, P smaller than 0.1) and CyIx (26 plus or minus 8 per cent, P smaller than 0.02). We conclude that, in the intact organism, with a normal myocardium or a diffuse or segmental myocardial disease, the administration of angiotensin results in a depression of contractility.

Acute myocardial infarction in toxic cardiomyopathy without coronary obstruction

Confluent left ventricular scar without significant coronary obstruction has been found in alcoholic subjects at autopsy. To evaluate the pathogenesis, 12 patients with chronic alcoholism and severe precordial pain persisting 4-24 hours were observed clinically. Cardiac isoenzymes of lactic dehydrogenase rose in serum. ST segment was elevated in anterior or posterior ECG leads, and abnormal Q waves appeared. Hypertnesion and hypercholesterolemia were present in two (group B) but not in the ten (group A). The latter exhibited no significant obstructive disease, based on coronary angiography in seven survivors and postmortem examination of the remaining three. Clinical evidence, as well as the quantitative assessment of platelets, made arterial thromboembolism an unlikely cause for the symptoms. Neither hemotologic or systemic disease affecting myocardium was present. The morphology of the left ventricle in three autopsies was compared with that of patients with alcoholism who had no cardiac disease, cardiomyopathy, or an asymptomatic scar. All had accumulation of Alcian positive glycoprotein in the interstitium. The patients with cardiac disease also had interstitial fibrosis which was characterized, particularly in the acute infarction group, by concentric periarterial fibrosis. Restriction of coronary vasodilation by this process during periods of high blood flow requirements was postulated as a basis for infarction.

Depression of myocardial contractility with low doses of ethanol in normal man

Depression of myocardial contractility after ethanol ingestion in man has previously been shown only in patients with heart disease. In the present study, normal subjects, aged 23-30 years, ingested six ounces of 43% alcohol over a two hour period (Group I, 6 subjects) or a one hour period (Group II, 5 subjects). Systolic time intervals were measured every 15 min from simultaneous ECG, phonocardiogram and carotid pulse tracings. Heart rate, total electromechanical systole and left ventricular ejection time (LVET) were not changed at any time from pre-alcohol values and, except for a small (5 mm Hg) and transient change in diastolic pressure in Group II, aortic pressures also were unchanged. However, in Group I, after 60 min, at a blood ethanol of 74 ± 3 mg%, left ventricular depression was manifested by increased pre-ejection period (PEP) from 90 ± 2 to 96 ± 3.1 msec, isovolumic time (IVT) from 44 ± 3.5 to 52 ± 4 ( P < .01), and PEP/LVET ratio from 0.299 ± 0.009 to 0.323 ± 0.01 ( P < .05). Further depression occurred at two hours with blood ethanol at 111 ± 6 mg%. Doubling ingestion rate (Group II) produced reduction of left ventricular performance at 30 min at a blood level of 50 ± 3 mg%. Feeding of isocaloric sucrose in 5 subjects (Group III) as a control produced a decrease in PEP, IVT, and PEP/LVET. Thus, alcohol in nonintoxicating doses elicits a depression of cardiovascular function in normal unhabituated subjects.

Systolic time intervals as measures of the contractile state of the left ventricular myocardium in man

Previous studies relating systolic time intervals and measures of cardiac performance have suggested that the time intervals may be useful indices of myocardial contractility. To explore this possibility, systolic times and left ventricular (LV) performance and contractility were measured nearly simultaneously in 14 normal subjects and 56 patients with cardiac disease. Preejection period (PEP) and the ratio of PEP to LV ejection time (LVET) changed significantly with acute inotropic influences (exercise and isoproterenol), were normal in patients with right or left ventricular overloads in whom cardiac index and ejection fraction were depressed but contractile element velocity at peak dP/dt and the Frank-Levinson contractility index were normal, and were significantly abnormal in patients with either clinically evident or occult LV decompensation in whom the measures of contractility were reduced. Correlations of PEP and PEP/LVET with measures of both performance and contractility were insignificant for patients with valvular disease, shunts, or cor pulmonale and significant but weak for the entire series. However, in subjects with either normal left ventricles or cardiac disease confined to the left ventricle, PEP and PEP/LVET exhibited good correlations with measures of pump function and excellent correlations with measures of contractility. These results indicate that the systolic times are a valid measure of contractility which should prove useful in comparing patients with cardiac pathology confined to the LV myocardium and in following patients with extramyocardial hemodynamic lesions of constant severity.