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At least 73 records · Page 4Linked to original sources
PubMed1984

[Mechanical activity of the system of contractile proteins, energy supply of the myocardium and disruption of calcium transport in inflammatory lesions of the myocardium].

In rabbit experiments it has been shown that in toxico-allergic myocarditis the disordered utilization of ATP energy is responsible for acute insufficiency of the myocardial contractile function, which results in a marked energy deficiency due to mitochondrial damage, the Ca2+ absorbtion and binding by the fragmented sarcoplasmatic reticulum being diminished.

Animals↗
PubMed2003

Protection of myocardium by cyclosporin A and insulin: in vitro simulated ischemia study in human myocardium.

BACKGROUND: The efficacy of myocardial protection by cyclosporin A (CSA) and insulin was tested in human right atrial myocardial slices subjected to simulated ischemia and reoxygenation. METHODS: Slices of right atrial trabeculae were obtained from patients undergoing elective cardiac surgery. Trabeculae were incubated with oxygenated glucose containing phosphate buffered saline (O(2), G-PBS). After 30 minutes of stabilization the sections were exposed to 90 minutes of simulated ischemia (N(2), PBS without glucose) followed by 90 minutes reoxygenation (O(2), G-PBS). Cyclosporin A (0.2 micromol/L) or insulin (5 mU/mL) was added during the stabilization period prior the ischemia. Cell viability was measured by using 3-[4.5 dimethylthiazol 2-yl]-2,5-diphenyltetrazolium bromide (MTT), which is cleaved by active mitochondrial dehydrogenases of living cells. RESULTS: The viability of untreated slices (control) was 30.45% +/- 2.5% versus 52.65% +/- 4.4% in the CSA treated slices, p less than 0.001. The extent of protection by CSA was affected by oral antiglycemic drugs (glibenclamide). The effect obtained by CSA was inhibited by 5-hydroxydecanoate (5HD), a specific blocker of mitochondrial K(ATP) channels. Protection of the myocardial slices with insulin appears to be superior and not affected by the medication before surgery. This protection was maximal when insulin was present during both preischemic equilibration and reoxygenation periods (68.9% +/- 9.3% viability with insulin versus 33.2% +/- 6.9% in the control, p < 0.001). CONCLUSIONS: Protection of right atrial trabeculae slices with insulin is superior to that obtained with CSA and is independent of preoperative medication.

Cell Survival↗
PubMed1994

Functional significance of angiotensin receptors in human myocardium. Significant differences between atrial and ventricular myocardium.

We studied the effects of angiotensin (Ang) I and II in a variety of isolated human cardiac tissues contracting under physiological conditions (37 degrees C, 60 beats.min-1). Ang I and II consistently increased the peak developed force of human atrial muscles by 30-40%, an effect that was completely blocked by 10(-6) M saralasine, but not by the combination of prazosin and propranolol. However, neither Ang I or II had significant inotropic effects in right and left ventricular human preparations. We were also able to demonstrate that the positive inotropic effect of Ang II in human right atrial tissue is mediated by the AT1 receptor subtype but not the AT2 receptor subtype.

Angiotensin I↗
PubMed1989

Protection of the myocardium during global ischemia. Is crystalloid cardioplegia effective in the immature myocardium?

In pediatric cardiac operations, a high proportion of hospital deaths are believed to result from inadequate myocardial protection during the period of global ischemia. To investigate whether this may be due to an inherently lower resistance to myocardial ischemia or to the failure of conventional cardioplegia to afford adequate protection in the immature heart, we have conducted a series of studies with isolated hearts from neonatal (3 to 5 days old, body weight 6.3 to 13.4 gm) and adult (84 to 112 days old, 260 to 340 gm) rats. The efficacy of cardioplegia was assessed in neonatal hearts (n = 6 per group) subjected to various durations of normothermic ischemia, with and without a 2-minute preischemic infusion of the St. Thomas' Hospital cardioplegic solution. At all times studied, the use of cardioplegia resulted in a greater postischemic recovery of left ventricular developed pressure and first derivative of left ventricular pressure. After periods of ischemia lasting 30, 60, 90, 120, and 150 minutes in the absence of cardioplegia, left ventricular developed pressure recovered to 80% +/- 10%, 66% +/- 11%, 53% +/- 7%, 33% +/- 6%, and 21% +/- 4% of preischemic values, respectively; in the presence of cardioplegia, the values were 89% +/- 6%, 83% +/- 8%, 74% +/- 6% (p less than 0.05), 58% +/- 5% (p less than 0.05), and 41% +/- 7% (p less than 0.05), respectively. The corresponding values for first derivative of left ventricular pressure were 78% +/- 9%, 67% +/- 12%, 54% +/- 7%, 30% +/- 5%, and 19% +/- 3% in the absence of cardioplegia and 92% +/- 7%, 88% +/- 8%, 75% +/- 8%, 56% +/- 5% (p less than 0.05) and 39% +/- 6% (p less than 0.05) in the presence of cardioplegia. In the noncardioplegia groups, 90% of hearts exhibited ischemic contracture (mean time to onset = 24.7 +/- 1.1 minutes), whereas in the cardioplegia groups, only 63% exhibited contracture, and of a significantly delayed onset (37.0 +/- 1.5 min, p less than 0.05). Adult hearts (n = 5) subjected to 30 minutes of normothermic ischemic arrest, in the absence of cardioplegia, recovered 36% +/- 7% of the preischemic left ventricular developed pressure and 37% +/- 9% of the preischemic first derivative of left ventricular pressure on reperfusion; 100% of these hearts exhibited some degree of contracture (mean time to onset = 15.4 +/- 1.1 minutes) by the end of the ischemic period.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

[Thallium-201 scintigraphy of the myocardium during exertion in the indication for aortocoronary bypass of an area in the myocardium, the site of an infarct].

The purpose of this study is to precisely evaluate the indications and the results of direct revascularization surgery in a myocardial area previously infarcted. 35 cases were analyzed using thallium scintigraphy during stress. Before surgery, the patients were divided in two groups. Group I (18 cases) includes patients who presented initially a regional hypoperfusion and a reperfusion at the site of the infarction, on late scintigrams; group II (17 cases) also presented a regional hypoperfusion initially, but showed no reperfusion on late scintigrams. Concerning the results during stress, the thallium 201 scintigrams during exercise show alterations of the myocardial perfusion in the infarcted area, before and after surgery; in group I, a significant improvement (p less than 0.01) is noted in the entire group, i.e. 16 patients (88.9%), except in 2 cases where the graft was occluded, and group II shows an improvement in only 4 cases (NS) after surgery. Concerning the modifications of the product pressure X cardiac rhythm, there is a significant improvement (p less than 0.01) in group I (14 out of 18 patients (77.8%)); 2 out of 4 patients who were aggravated, presented occluded grafts after surgery. Group II shows an improvement in 10 out of 17 patients (58.8%) after surgery (NS). The left ventriculography demonstrates alterations in the global ejection fraction. Group I shows a significant improvement in 15 out of 18 patients (88.3%) (p 0.01); in group II there is improvement in 11 out of 17 patients (64.7%) (NS) after surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1975

[Steinert's syndrome and the myocardium. Total gene expression by the myocardium].

As revealed by a very thorough cardiological study of Steinert's disease in 13 cases, it would appear that the incidence of cardiac involvement observed in this disease is not merely frequent; it is, in fact, usual, systematic, and forms an integral part of the pathological picture in the same way as peripheral muscular dystrophy. One is aware of the diagnostic interest of this fact in the juvenile or abortive forms of the disease. The cardiac involvement is an indication of the complete expression of the gene towards striated muscle tissue, whether skeletal or myocardial. Finally, it opens new perspectives on the prophylactic attitude to be adopted for such patients; regular and systematic cardiological checks, moderation in the prescription of digitalis and anti-arythmia drugs, implantation of a cardiac pacemaker before an auriculo-ventricular syncopal block occurs.

Adolescent↗