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Biomedical subjects

S C Manchanda

Publications and source records attributed to S C Manchanda.

At least 73 records · Page 4Linked to original sources
PubMed1985

Alterations in isoproterenol-induced cardiac metabolic changes by a quaternary analog of propranolol, UM-272.

Effect of UM-272, a dimethyl propranolol has been studied in experimental myocardial necrosis induced by isoproterenol (ISP, 85 mg/kg, SC X 2 days) in rats. Administration of ISP caused increased serum creatine phosphokinase (CPK), lactate dehydrogenase (LDH) and decreased myocardial glycogen, adenosine triphosphate (ATP) creatine phosphate (CP) and glycolysis through phosphofructokinase (PFK). Myocardial tissue lactate was markedly increased. All these changes resulted in development of myocardial necrosis as calculated from the CPK depletion from the injured myocardium. Rats given UM-272 (10 mg/kg or 20 mg/kg i.p.) 5 days before and 2 days during ISP administration showed significant improvement in all the parameters studied. Furthermore, UM-272 (20 mg/kg X 7 days) in control rats caused a significant (P less than .001) increase in ATP and CP content of the myocardium while other parameters remained unaltered. It would appear from the present study that the cardioprotective effect in ISP induced injury is not related to beta blockade as UM-272 is devoid of beta-blocking properties.

Animals↗
PubMed1984

Oxyfedrine and propranolol. A comparative experimental approach to protect myocardium against isoprenaline-induced myocardial necrosis.

Myocardial necrosis was produced in rats by isoprenaline (ISP) administration (85 mg X kg-1 s.c.) for two consecutive days. Rats sacrificed at 12, 24, 30, 36 and 48 h, respectively, after the last injection of ISP showed a marked increase in serum enzymes, viz. creatine phosphokinase (CPK), lactic dehydrogenase (LDH) and aspartate transaminase (AST) and tissue content of lactate. In addition, there was a significant reduction in the glycogen content of myocardium and the activity of enzyme phosphofructokinase (PFK) was changed in biphasic fashion, i.e. initial enhancement of activity was followed by a persistent fall. All these changes were present along with typical infarct-like necrosis as seen microscopically. Both oxyfedrine (OXF, 2, 4 and 8 mg X kg-1 i.m.) and propranolol (PROP, 1, 2 and 4 mg X kg-1 i.m.) administered for 5 days before and two days during ISP administration were effective in providing protection. However, with 8 mg X kg-1 dose of PROP sporadic high mortality was observed. Serum AST and CPK levels in OXF (4 and 8 mg X kg-1) and PROP (2 and 4 mg X kg-1) pretreated animals returned back to the range of controls. Unlike OXF, the LDH level in PROP pretreated rats, though reduced significantly, remained always higher than the control values. The beneficial effect of OXF on myocardial glycolytic flux was dose-dependent. 8 mg X kg-1 of OXF increased (31%) the glycogen content significantly (p less than 0.01) and the activity of enzyme PFK and tissue lactate content were brought back to normal. PROP did not exhibit dose-dependent reduction in the lactate content of the myocardium and it was never restored back to the range of control values.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Nature of the beta-adrenoreceptors in the tracheal smooth muscle of the adult pig.

Relaxant responses to isoprenaline (ISO), adrenaline (ADR) and noradrenaline (NA) were investigated on carbachol-contracted, isolated tracheal smooth muscle preparations of the adult pig to determine the nature of the beta-adrenoreceptors present. The order of relaxant potencies of the catecholamines on this preparation was ISO greater than ADR greater than NA. The potency ratio at 37 degrees C was 1:0.06:0.005. This suggests that beta 2-adrenoreceptors predominate in isolated tracheal smooth muscle of the adult pig. Though the order of potency for the above catecholamines did not change, at the lower temperatures of 29 degrees and 33 degrees C, the potency ratios were slightly modified to 1:0.0.98:0.004 and 1:0.07:0.004 respectively. pA2 values on pig tracheal smooth muscle were 8.65 and 9.13 respectively, for the non-selective beta-blockers propranolol and alprenolol, and 5.63, 5.20 and 6.26 respectively, for the beta 1 selective blockers practolol, atenolol and metoprolol and 6.82 for the beta 2 selective beta-blocker, H 35/25. The results suggest the existence and predominance of beta 2-adrenoreceptors in tracheal smooth muscle of the adult pig.

Adrenergic beta-Agonists↗
PubMed1983

Cardiac involvement in myasthenia gravis.

Non-specific ECG changes and histological changes in the myocardium in patients with myasthenia gravis (MG) have been described. In this study, the left ventricular function using systolic time intervals (STI) was assessed in patients with MG. 4 patients out of the 10 studied showed abnormalities of the STI which reverted towards normal after injection of neostigmine. This finding suggests that myocardial involvement in MG may be more common than clinically suspected.

Adolescent↗
PubMed1982

Mitral valve prolapse and cerebrovascular accidents in the young.

The incidence of stroke in the young is reported to be high in India. The role of the mitral valve prolapse (MVP) syndrome in these patients is not clear. A prospective study over a period of 1 year was carried out in order to evaluate the role of MVP in cases of stroke occurring in patients below the age of 40 years. Of the 38 cases of stroke in the young seen during this period, well-recognised risk factors of stroke could be detected in 17. MVP confirmed by M-mode echocardiography was seen in 13% of all stroke patients and in 23.8% of those in which there were no other risk factors. The incidence of MVP was much higher if only the clinical criteria for diagnosis were used. We believe that MVP is a significant risk factor in younger stroke patients, and, in such cases, merits investigation. The probable pathogenic mechanisms and therapeutic implications are discussed.

Adolescent↗
PubMed1982

Interaction of ouabain and propranolol in the central nervous system. Neurally-mediated effects on the cardiovascular system.

The effect of intracerebroventricular (i.c.v.) ouabain alone and after pretreatment with i.c.v. (+/-)-propranolol, (+)-propranolol, UM-272 (a quaternary analogue of propranolol) and lignocaine, on arterial blood pressure (BP), heart rate (HR) and cardiac rhythm was investigated in chloralose anesthetized, vagotomized cats. Ouabain elicited an increase in BP and HR followed by cardiac arrhythmias of ventricular origin. Pretreatment with (+/-)-propranolol, (+)-propranolol or UM-272 attenuated/prevented the cardiovascular effects of ouabain whereas lignocaine did not modify the response appreciably. Since UM-272, which lacks local anesthetic activity and beta-blocking activity also shared the antagonism with (+/-)-and (+)-propranolol, it is deduced that neither beta-blocking nor local anesthetic activity of propranolol could be responsible for this antagonism. This is supported by the fact that lignocaine which has a comparable local anesthetic effect of propranolol failed to modify significantly the cardiovascular response to ouabain. The antagonism appears to be a direct neural depressant effect independent of local anesthetic action. The neural depressant effect may be due to an interference in depolarization process and/or a neurone-blocking effect.

Animals↗
PubMed1981

Reduced physical work capacity at high altitude--a role for left ventricular dysfunction.

Physical work capacity is reduced in sea level residents--lowlanders (LL) as compared to high altitude residents--highlanders (HL). To determine possible etiologies, cardiac performance was studied in two groups of healthy male volunteers (13 LL and 11 HL) utilizing systolic time intervals during rest, submaximal and maximal exercise. The LL were studied at sea level and subsequently during 10 days of residence at an altitude of 3658 m. The HL were studied at high altitude alone. The LL were restudied 30-45 min after administration of intravenous furosemide at high altitude. Mean maximal oxygen uptake (VO2max) was reduced by 26% in the LL group at high altitude in comparison to sea level values and by 20% in relation to the HL group. Cardiac performance was estimated by the pre-ejection period/left ventricular ejection time ratio. This index was significantly increased in the LL group at high altitude in comparison to sea level values during submaximal and maximal exercise (P less than 0.01). Intravenous furosemide in the LL group increased the heart rate (P less than 0.05) at rest and during exercise but VO2max and cardiac performance were unchanged. It is hypothesized that reduced physical work capacity at high altitude in the LL group may be related to depression of cardiac performance in these subjects. Administration of intravenous furosemide did not influence cardiac performance in the LL group at high altitude.

Adult↗
PubMed1981

Cardiovascular response to electrical stimulation of and microinjection of ouabain into posterior and ventromedial hypothalamus of cat.

Electrical stimulation (ES) of and injection of ouabain into ventromedial hypothalamus (VMH) of cats elicited only minor changes in heart rate (HR) and blood pressure (BP). On the other hand similar treatments to posterior hypothalamus (PH) consistently produced a significant increase in HR and BP; two out of five animals developed cardiac arrhythmias. The study suggests that PH is a potential site of action of ouabain for induction of arrhythmias.

Animals↗
PubMed1980

Apexcardiography.

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Heart Diseases↗
PubMed1979

Haemodynamic studies in veno-occlusive disease of the liver.

Haemodynamic studies in 8 tribal patients from central India with veno-occlusive disease of the liver are reported. The disease was caused by eating cereals contaminated with seeds of a crotalaria species rich in toxic pyrrolizidine alkaloids similar to monocrotaline and fulvine. All patients showed raised hepatic venous wedge pressures and pressure gradients between hepatic venous wedge and free hepatic vein. Significant pressure gradients were also observed in the inferior vena cava. Right and left heart pressures were normal. Cardiac and stroke indices and ventricular work were significantly increased while systemic and pulmonary resistances were reduced. Hepatic blood flow was also reduced. Hepatic venograms were abnormal and the changes correlated well with the pressure gradients between hepatic venous wedge and free hepatic vein and with the histological changes in the liver.

Adolescent↗
PubMed1979

Primary angiosarcoma of the heart.

An unusual case of primary angiosarcoma of the left atrium in a heart with chronic rheumatic valvulitis is described. The tumor which was detected at autopsy 2 years after the second valvotomy operation was restricted to the endocardium only and metastasized to the brain.

Adult↗