Biomedical subjects

G Kober

Publications and source records attributed to G Kober.

At least 19 recordsLinked to original sources

PubMed1992

Wiktor stent implantation in patients with restenosis following balloon angioplasty of a native coronary artery.

Intracoronary stenting has been introduced as an adjunct to balloon angioplasty aimed at overcoming its limitations, namely acute vessel closure and late restenosis. This study reports the first experience with the Wiktor stent implanted in the first 50 consecutive patients. All patients had restenosis of a native coronary artery lesion after prior balloon angioplasty. The target coronary artery was the left anterior descending artery in 26 patients, the circumflex artery in 7 patients and the right coronary artery in 17 patients. The implantation success rate was 98% (49 of 50 patients). There were no procedural deaths. Acute or subacute thrombotic stent occlusion occurred in 5 patients (10%). All 5 patients sustained a nonfatal acute myocardial infarction. Four of these patients underwent recanalization by means of balloon angioplasty; the remaining patient was referred for bypass surgery. A major bleeding complication occurred in 11 patients (22%): groin bleeding necessitating blood transfusion in 6, gastrointestinal bleeding in 3 and hematuria in 2. Repeat angiography was performed at a mean of 5.6 +/- 1.1 months in all but 1 patient undergoing implantation. Restenosis, defined by a reduction of greater than or equal to 0.72 mm in the minimal luminal diameter or a change in diameter stenosis from less than to greater than or equal to 50%, occurred in 20 (45%) and 13 (29%) patients, respectively. In this first experience, the easiness and high technical success rate of Wiktor stent implantation are overshadowed by a high incidence of subacute stent occlusion and bleeding complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗

PubMed1992

Long-term follow-up after percutaneous transluminal coronary angioplasty in patients with single-vessel disease.

Seven hundred ninety-eight patients with symptomatic single-vessel disease who underwent percutaneous transluminal coronary angioplasty (PTCA) between 1977 and 1985 were reevaluated by questionnaire 78 +/- 23 months after dilatation. Indication for PTCA was stenosis of > or = 70%, anginal symptoms, and objective signs of myocardial ischemia. The immediate success rate was 81.2%, and severe complications occurred in 7.1%, which included two fatal complications (0.3%). Repeat angiograms were performed in 582 of 648 patients who underwent successful dilatation and showed restenosis in 143 cases (24.6%). Within 1 year after the first dilatation, 586 patients had been successfully revascularized by PTCA (i.e., there was no evidence of restenosis or redilatation was successful), and 113 patients had undergone bypass surgery. The remaining 99 patients were treated medically if PTCA was unsuccessful or if restenosis (> or = 70%) that was not amenable to redilatation was present. The 8-year overall survival probability was 91.7%, and cardiac survival was 95.5%. The 8-year event-free survival probability was 52.7% for all patients: 62.5% in patients who had successful PTCA and 14.5% in patients who had unsuccessful PTCA (p = 0.0000). The cardiac survival probabilities of patients with lasting PTCA success at 1 year and of surgically treated patients were significantly better than those of patients who did not have successful revascularization (at 8 years 97.2% and 98.1% vs 88.9%; p < 0.04). Late events (> or = 1 year) occurred more often in patients who did not have successful revascularization compared with patients who had successful PTCA (at 8 years 57.9% were event-free vs 74.4%; p < 0.0001); even fewer late events were observed in surgically treated patients (at 8 years 88.2% were event-free; p < 0.004). Cox's proportional hazards regression analysis revealed left ventricular ejection fraction and revascularization status at 1 year as determinants of overall, cardiac, infarct-free, and event-free survival probabilities. At the time of reevaluation significantly more patients in the successful PTCA subgroup were still free of symptoms or had experienced improvement than patients in the bypass or medical subgroups (86.8% vs 68.9% and 59.5%, respectively; p < 0.0001), and more patients in the successful PTCA subgroup were still working (75.4% vs 53.3% and 56.9%, respectively; p < 0.001). We concluded that patients with single-vessel disease who have undergone successful dilatation have an excellent long-term prognosis with regard to survival, cardiac symptoms, and vocational status.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗

PubMed1992

Myocardial protection during percutaneous transluminal coronary angioplasty: effects of trimetazidine.

Trimetazidine (TMZ) has recently been shown to improve anginal symptoms without altering haemodynamic variables. A randomized, double-blind, placebo-controlled study was conducted in 20 patients to study the effects of TMZ on the severity of myocardial ischaemia during PTCA of the left anterior descending coronary artery. Five minutes after a first successful dilatation (D0), a control balloon inflation (D1) was performed until onset of ischaemic signs on both the intracoronary (i.c.) and precordial ECG. Two minutes later, patients received either TMZ 6 mg or placebo i.c. Another inflation (D2) was performed 5 min after D1. No differences were found between the two groups regarding responses in heart rate, systemic and i.c. pressures during the study. TMZ decreased the maximum ST-segment shift at D2 compared with D1 (0.8 +/- 0.1 vs 1.4 +/- 0.3 mV, P = 0.023) and delayed its onset (46 +/- 4 vs 36 +/- 5 s, P = 0.024). TMZ also decreased maximum T-wave changes (1.06 +/- 0.24 vs 2.19 +/- 0.3 mV, P = 0.001), and significantly reduced the area under the curve (mv s-1) of the i.c. ST-segment and T-wave changes during balloon inflation (P = 0.042 and P = 0.009 respectively). The placebo had no effect on these parameters. These results support the hypothesis that trimetazidine has a direct anti-ischaemic effect on human myocardial cells.

Angioplasty, Balloon, Coronary↗

PubMed1992

Comparison of negative inotropic and vasodilator effects of isradipine and nifedipine after complete autonomic blockade in ischemic heart disease.

The cardiodepressant and vasodilator effects of an intravenous (i.v.) infusion of 0.5 mg isradipine or 2 mg nifedipine were interindividually (10 vs. 10 patients) compared in a double-blind study in patients with stable coronary heart disease. To minimize vasodilation-induced autonomic reflex mechanisms, which may counterbalance negative inotropic effects after acute administration of calcium antagonists, i.v. autonomic blockade was produced by 0.2 mg/kg propranolol and 0.04 mg/kg atropine. Systemic hemodynamics were measured before and 15 min after the end of the 15-min calcium antagonist infusion. After administration of both drugs, heart rate (HR) decreased similarly during the observation period (isradipine from 93 +/- 10 to 88 +/- 9 beats/min and nifedipine from 84 +/- 9 to 79 +/- 6 beats/min, both p less than or equal to 0.01). The reduction in total peripheral resistance (TPR) was significantly (p less than or equal to 0.01) greater after isradipine (from 1,376 +/- 285 to 1,002 +/- 224 dynes s cm-5) than after nifedipine (1,258 +/- 262 to 1,112 +/- 225 dynes s cm-5). Between the two drugs, the difference in the reduction of afterload independent dP/dt40, determined by tip-manometry, reached borderline significance (p = 0.08) (isradipine from 1,197 +/- 258 to 1,157 +/- 225 mm Hg/s, NS and nifedipine 1,228 +/- 226 to 1,109 +/- 227 mm Hg/s, p less than or equal to 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Autonomic Nerve Block↗

PubMed1992

Effect of propranolol and disopyramide on left ventricular function at rest and during exercise in hypertrophic cardiomyopathy.

In 19 patients with hypertrophic cardiomyopathy (15 males, 4 females, mean age 49.2 +/- 10.8 years) left ventricular function was studied with radionuclide ventriculography at rest and during exercise in a crossover design without intervention and after disopyramide and propranolol treatment. 15 of the 19 patients had a resting or latent intraventricular gradient of more than 30 mm Hg. Left ventricular function at rest and during exercise was evaluated before medication, 90 min after oral administration of 200 mg disopyramide or 160 mg propranolol and after 3 weeks of oral therapy with disopyramide 200 mg 2 times a day or propranolol 80 mg 4 times a day. After long-term treatment with disopyramide, resting ejection fraction decreased from 72 +/- 12 to 69 +/- 14% (p less than 0.01) and peak ejection rate (PER) decreased from 3.46 +/- 135 to 3.24 +/- 65 end-diastolic volume (EDV).s-1 (p less than 0.01). Peak filling rate (PFR) at rest decreased from 3.01 +/- 0.8 to 2.77 +/- 0.63 EDV.s-1 (p less than 0.05). Time to peak filling rate (TPFR) at rest and during exercise after acute and chronic therapy did not change compared to control values. Acute and long-term administration of propranolol lead to a significant reduction in heart rate at rest and during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗

PubMed1992

Can the coronary atherosclerotic process be influenced by calcium antagonists?

Cell culture experiments and various animal models have shown that calcium antagonists can inhibit atheroma development. A number of antiatherosclerotic mechanisms have been proposed and the promising results of these in vitro and animal experiments prompted clinical trials. Retrospective analyses indicated that verapamil might retard disease progression and the development of new stenoses. Prospective clinical studies, however, have revealed no effect by calcium antagonists on pre-existing coronary stenoses (> or = 20%) and it is suggested that the study duration (2 to 3 years) may have been too short and that advanced stages of atheromatous disease are not influenced by calcium antagonists. Current data suggest that only early stages of coronary atheromatosis may be affected by treatment with calcium antagonists; however, optimum drug, dosage and suitable patients are yet to be defined.

Animals↗

PubMed1992

Effect of magnesium pyridoxal 5-phosphate glutamate on the hamster cardiomyopathy.

30-day-old polymyopathic hamsters (strain BIO 82.62) were orally treated with either magnesium pyridoxal 5-phosphate glutamate 100 mg/kg, equimolar amounts of magnesium alone (MgCl2 55 mg/kg), or water b.i.d. for 30 days, or sacrificed before treatment. 60-day-old healthy hamsters (strain CLAC) served as controls. Magnesium pyridoxal 5-phosphate glutamate lowered the myocardial calcium content (42.8 +/- 13.1 mmol/kg dry weight) as compared to MgCl2 (70.3 +/- 11.9 mmol/kg dry weight) and water (72.7 +/- 13.6 mmol/kg dry weight). The serum and tissue lipid pattern did not differ between BIO 82.62 and normal hamsters except high serum cholesterol and triglyceride levels in 30-day-old BIO 82.62 hamsters. Myocardial necroses were influenced by neither magnesium pyridoxal 5-phosphate glutamate nor MgCl2. Cytochemical investigation of the ultrastructural calcium localization in the aorta revealed less calcium precipitates with magenesium pyridoxal 5-phosphate glutamate in media myocytes. It is concluded that magnesium pyridoxal 5-phosphate glutamate exerts a calcium antagonistic effect in the cardiomyopathy of the Syrian hamster which is related neither to the magnesium content of magnesium pyridoxal 5-phosphate glutamate nor to its lipid lowering activity.

Animals↗

PubMed1991

[Changes in the blood and plasma volumes during diagnostic angiocardiography. Differences between high- and low-osmolality contrast media].

Changes in blood and plasma volumes were investigated in the course of diagnostic cardiac catheterizations, comparing the effect of a high and a low osmolar contrast medium in 30 patients (5 women and 25 men; mean age 53 [19-76] years) with coronary heart disease (n = 27) or valvular defect (n = 3). Using a randomized, double-blind protocol 15 patients received amidotrizoic acid (2.1 osmol/kg; mean dosage 166 +/- 68 or 2.2 +/- 1.1 ml/kg), while 15 patients received iopamidol (0.8 osmol/kg; mean dosage 154 +/- 78 ml or 2.1 +/- 1.0 ml/kg). The indocyanine-green method and the haematocrit were used to measure blood and plasma volumes immediately before and after the angiocardiography. Blood volume after amidotrizoic acid injection increased by a mean of 4.9% (228 +/- 242 ml) and by 0.4% (17 +/- 197 ml) after iopamidol (P less than 0.05). Plasma volume increased by a mean of 11.8% (331 +/- 150 ml) after amidotrizoic acid and 5.7% (157 +/- 97 ml) after iopamidol (P less than 0.01). The increase in plasma volume correlated with the dose of contrast medium: 2 ml per ml amidotrizoic acid (r = 0.93) and 1 ml per ml iopamidol (r = 0.82).--During angiocardiography blood and plasma volume may increase by up to 500 ml, an increase which depends not only on dosage but also on the osmolality of the injected contrast medium.

Adult↗

PubMed1991

[20 years of selective coronary angiography (1968-1987). The indications, results and therapeutic consequences].

10,975 diagnostic left-heart catheterizations, performed between 1968 and 1987 in 8,436 men and 2,539 women, were analysed regarding indication, results and therapeutic implications. 6,974 patients (64%) had coronary heart disease, 2,573 (23%) a valvar defect and 849 a cardiomyopathy. The proportion of patients with coronary heart disease increased from 21% to 74% during the 20-year period, while that of patient with valvar defects fell from 52% to under 19%. Severe cardiac complications in relation to the procedure occurred in 0.88%, ending fatally in 8 patients (0.07%). 61% of patients with coronary heart disease and 31% of those with valvar defects were treated conservatively. Percutaneous transluminal coronary angioplasty (PTCA) gradually became more common after its introduction in 1977. In 1987, PTCA was indicated as often as a bypass operation.

Age Factors↗

PubMed1991

[Successful directional coronary atherectomy after futile attempts at balloon dilatation].

Coronary arteriography revealed severe stenoses of the proximal part of the anterior interventricular branch with normal ventricular function in two patients (aged 42 and 38 years) with stable angina and ischaemia reaction in the exercise ECG. In the first patient it was a short spur-like 80% narrowing. But percutaneous balloon angioplasty failed to change the angiographic appearance. In the other patient there was an eccentric, apparently elastic, 90% stenosis, about 10 mm long. Here, too, balloon angioplasty had failed. Subsequently directional coronary atherectomy in both patients achieved removal of the stenosis with lasting clinical improvement. Atherectomy should be considered in similar cases after failed balloon dilatation.

Adult↗

PubMed1991

Morphologic change in coronary artery stenosis with the Medtronic Wiktor stent: initial results from the core laboratory for quantitative angiography.

The purpose of this study was to assess the early changes in stenosis geometry after implantation of the Medtronic Wiktor stent in human coronary arteries. Morphologic changes were evaluated by quantitative coronary angiography using automated edge detection. The hemodynamic significance of the morphologic changes were assessed by the calculation of the theoretical pressure drop across the dilated and stented stenosis derived from the Poiseuile and turbulent resistances assuming a coronary blood flow of either 0.5, 1, or 3 ml/sec. Fifty patients were studied before and immediately after stent implantation. The stented coronary artery was the left anterior descending artery in 26 patients, the circumflex artery in eight patients, and the right coronary artery in 16 patients. Stent implantation resulted in an additional increase in the minimal luminal cross-sectional area and minimal luminal diameter of the dilated vessel without changing the curvature of the stenosis. Furthermore, there was a significant reduction of the "plaque area." This was associated with a normalization of the calculated resistances to flow and pressure drop across the stenosis. To a minimal extent, recoil (0.1 +/- 0.36 mm) was observed after stent implantation.

Adult↗

PubMed1991

Acute and chronic effects of nitrendipine in patients with precapillary pulmonary hypertension due to pulmonary fibrosis.

Eleven patients with histologically confirmed fibrosis of the lung were investigated for the effects of the dihydropyridine calcium antagonist nitrendipine on pulmonary hemodynamics. After 5 mg of acute sublingual nitrendipine, mean pulmonary artery pressure was significantly lowered (p less than or equal to 0.05) from 32 +/- 3 to 29 +/- 3 mmHg at rest, and significantly lowered (p less than or equal to 0.05) during exercise from 55 +/- 4 to 49 +/- 4 mmHg. Short-term oxygen application at rest significantly reduced this parameter to 28 +/- 3 mmHg (p less than or equal to 0.001). Nitrendipine lowered total pulmonary vascular resistance during both rest (from 412 +/- 50 to 351 +/- 49 dyn.s.cm-5; p less than or equal to 0.05), although it did not affect pulmonary arteriolar resistance. Also, oxygen treatment at rest influenced only total pulmonary vascular resistance (reduction from 412 +/- 50 to 373 +/- 48 dyn.s.cm-5; p less than or equal to 0.01), but not pulmonary arteriolar resistance. Pressure-flow curves, which were derived from cardiac output at rest and during exercise and from the corresponding gradient between mean pulmonary artery pressure and pulmonary capillary wedge pressure, remained unchanged by acute medication. Since a change in arterial oxygen partial pressure was not noticed after nitrendipine, arteriovenous shunting or a worsening of ventilation perfusion relationships can be excluded. Long-term (3 weeks) treatment (double-blind parallel design) with 10 mg of nitrendipine (4 patients) once daily showed no advantage in comparison to placebo (6 patients).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Expression of different CD8 isoforms on distinct human lymphocyte subpopulations.

Human CD8+ lymphocyte subpopulations were analyzed for their expression of CD8 alpha and CD8 beta subunits. Investigations with uncloned peripheral blood lymphocytes as well as cloned human natural killer and T cell subpopulations demonstrate that CD3- natural killer cells, T cell receptor gamma/delta, and CD4+CD8+ T cell clones express exclusively CD8 alpha gene products. Structural analysis of CD8 molecules demonstrates that CD8 alpha+/beta- T lymphocytes surface express 75-kDa CD8 alpha/alpha homodimers whereas CD8 alpha/beta lymphocytes express concomittantly two CD8 isoforms of different molecular masses (67 kDa and 75 kDa, respectively). Peptide mapping of these latter two isoforms suggests that CD8 is expressed as alpha/alpha homodimers and alpha/beta heterodimers on CD8 alpha/beta+ cells. Importantly, we found that the two CD8 isoforms behave functionally different. Thus, in contrast to CD8 alpha/beta+/CD8 alpha/alpha+ T lymphocytes, cytolytic activity of CD8 alpha/beta-/CD8 alpha/alpha+ T cell clones was not inhibited by anti-CD8 monoclonal antibodies and the latter were not induced to proliferate following CD3/CD8 cross-linking.

Antibodies, Monoclonal↗

PubMed1991

Response of coronary arteries to nitrates, the EDRF-donor SIN-1, and calcium antagonists.

Intracoronary drug administration is an important tool to study coronary effects without interaction of systemic effects. The difficult methodological aspects and the results of clinical trials in which the effects of vasodilating drugs were evaluated with respect to coronary dilatation are reviewed. Major (coronary substrate, study design) and minor (measuring devices, methods of evaluation) methodological problems make it difficult to precisely evaluate pharmacological effects such as dose-response relationship, duration of action, and selective responses, and to compare the effects of different drugs. From a clinical point of view, knowledge of the maximal effect (EDmax) in coronary stenoses and the duration of action is essential. NO-donors tend to act stronger than CA-channel blockers which may be attributable to their different modes of action. Among those NO-donors investigated, SIN-1 showed stronger effects than nitroglycerin. Only with SIN-1 were maximal effects obviously achieved. The additional administration of nitroglycerin or nisoldipine never led to a more prominent dilatation. In coronary stenoses, the underlying morphology causes a wider range of responses than is seen in normal segments: deendothelialized stenoses with high coronary tone show a larger dilatation, while fully sclerotic stenoses may not react.

Calcium Channel Blockers↗

PubMed1991

Right ventricular volumes determined by computerized thermodilution in ischaemic heart disease: effect of exercise and nitroglycerin.

In 29 patients with stable ischaemic heart disease, right heart catheterization was performed to assess the effect of exercise and nitroglycerin on right ventricular volumes, which were determined by a new computerized thermodilution system. The coefficient of variation for the determination of right ventricular ejection fraction averaged 11.0 +/- 6.2% (mean +/- standard deviation) at rest and 14.6 +/- 8.1% during exercise. End-diastolic volume index increased from 90 (65-127) ml/m2 [median (range)] at rest to 101 (81-130) ml/m2 (P less than or equal to 0.0001) during exercise. Nitroglycerin reduced this parameter at rest to 77 (44-121) ml/m2 (P less than or equal to 0.05), without affecting exercise values. Resting right ventricular ejection fraction (55 [44-64]%) was diminished by both exercise (to 52 [39-62]%, P less than or equal to 0.05) and nitroglycerin (to 53 [40-65]%, P less than or equal to 0.05). Additionally, nitroglycerin reduced the exercise induced decrease of right ventricular ejection fraction from -3 (-20-10)% to -1 (-15-14)% (P less than or equal to 0.01). Nitroglycerin diminished the left-to-right interventricular end-diastolic pressure gradient, which was estimated from the difference between pulmonary capillary wedge pressure and right atrial pressure, at rest from 6 (1-17) mmHg to 5 (2-14) mmHg (P less than or equal to 0.05) and during exercise from 17 (6-31) mmHg to 14 (1-33) mmHg (P less than or equal to 0.001). It is concluded, that both exercise and nitroglycerin cause significant changes in right ventricular volumes.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗

PubMed1991

Beat-to-beat variation of heart rate in diabetic patients with autonomic neuropathy and in completely cardiac denervated patients following orthotopic heart transplantation.

Dysfunction of the vagal nerve, an early symptom in the development of autonomic neuropathy, can be assessed reliably by the beat-to-beat variation in heart rate. Patients after a cardiac transplantation are a unique model to investigate the beat-to-beat variation of a completely denervated heart. Heart rate and the beat-to-beat variation during normal and deep respiration were investigated in diabetic subjects with an autonomic neuropathy (n = 10), age and sex matched healthy controls (n = 10) and cardiac transplanted patients (n = 10). Further studies during pharmacological blockade of the parasympathetic nervous system with atropine were performed. In the denervated heart the coefficient of variation of the beat-to-beat interval was 0.38 +/- 0.02% during normal respiration, compared to 1.32 +/- 0.13% (P less than 0.0001) and 2.56 +/- 0.13% (P less than 0.0001) in the diabetic and control subjects, respectively. Administration of atropine (2 mg intravenously) decreased the coefficient of variation of the RR-interval to 0.73 +/- 0.09% in the diabetic patients (P less than 0.0005) and to 0.67 +/- 0.07% in the controls (P less than 0.0001), whereas the coefficient of variation remained unaffected in the cardiac denervated patients (0.39 +/- 0.02%). In the three groups an almost parallel increase of the RR-variation was observed during deep respiration at a rate of 6 breaths/min (from 0.38 +/- 0.02% to 1.99 +/- 0.38% in cardiac transplanted patients, P less than 0.0025; from 1.32 +/- 0.13% to 3.10 +/- 0.43% in diabetic patients, P less than 0.0025; from 2.56 +/- 0.13% to 5.42 +/- 0.94% in healthy controls, P less than 0.005). We conclude that a beat-to-beat variation of heart rate is present in the completely denervated heart. This RR-variation can not be influenced by a pharmacological blockade of the parasympathetic nervous system with atropine. The beat-to-beat variation increases during deep respiration not only in healthy controls but also in diabetic patients with autonomic neuropathy (partially denervated hearts) and cardiac transplanted patients (completely denervated hearts). This indicates an intracardiac mechanism in the modulation of heart rate.

Atropine↗

PubMed1991

The effect of cyclosporine on electrically paced isolated rat cardiomyocytes.

The acute cardiotoxicity of cyclosporine was investigated in isolated cardiomyocytes from adult rats. In a first study, myocytes were incubated with CsA ranging from 1 to 10 micrograms/ml and paced by electrical-field stimulation. After 30 min of stimulation the number of surviving rod-shaped myocytes was significantly reduced at 2.5 micrograms/ml (77.9%) and 5 micrograms/ml CsA (64.2%) as compared with the drug vehicle methanol (88.8%, P less than 0.05) with a further decrease at 10 micrograms/ml CsA (30.1% vs. 81.2%, P less than 0.005). In a second study, with the use of digital image processing of fura-2 fluorescence, the mean intracellular free calcium concentration, integrated over 1 sec, of single myocytes in the presence of 5 micrograms/ml CsA, the solvent methanol, or pure Krebs Ringer Hepes buffer was measured. Starting 2 Hz field stimulation increased the intracellular free calcium concentration from 100.1 to 177.9 nM in buffer and from 145.7 to 200.6 nM calcium with methanol. In contrast, there was a 3-fold increase of the intracellular free calcium concentration with 5 micrograms/ml CsA from 128.8 to 376.1 nM calcium. The intracellular free calcium during electrical stimulation was significantly higher with CsA than with the solvent (376.1 nM vs. 200.6 nM, P less than 0.001). In a further study, myocytes were incubated with calcium ranging from 0.5 to 8 mM calcium in the presence of 5 micrograms/ml CsA or the solvent methanol and electrically stimulated. Here, with increasing extracellular calcium the number of rod-shaped myocytes decreased significantly with CsA as compared with the solvent (P less than 0.02). The data suggest that CsA exerts a dose-dependent toxic effect on isolated rat cardiomyocytes that depends on the extracellular calcium concentration. There is direct evidence that CsA increases the intracellular free calcium concentration in rat cardiomyocytes.

Animals↗

PubMed1991

[Neither propranolol nor the vasodilating beta-blocker carvedilol have a direct effect on coronary resistance vessels].

Seventeen patients with coronary heart disease were included in a double-blind randomized study. They received either 5 mg of carvedilol or 6 mg of propranolol intravenously. Heart rate, aortic pressure, mean coronary sinus pressure and coronary flow (thermodilution) were measured, and coronary resistance and rate-pressure product were calculated before and 15 min after the infusion, which lasted 10 min. Carvedilol lowered significantly (p less than 0.05) heart rate (mean 76 to 69/min), aortic pressure (mean 153/80 to 135/72 mm Hg), rate-pressure product (mean 117 to 93 mm Hg/min) and coronary flow (mean 114 to 94 ml/min). Coronary resistance and coronary flow related to rate-pressure product showed no significant change after carvedilol. Propranolol lowered heart rate (mean 76 to 64/min; p less than 0.05) and rate-pressure product (mean 109 to 96 mm Hg/min; ns). Aortic pressure, coronary flow, coronary resistance, and coronary flow related to rate-pressure product showed no significant change after propranolol. Thus, carvedilol lowered rate-pressure product more markedly than propranolol on account of its acute blood-pressure lowering effect. Neither drug seems to have a direct influence on coronary resistance vessels.

Adrenergic beta-Antagonists↗