Biomedical subjects

A Ezzaher

Publications and source records attributed to A Ezzaher.

6 recordsLinked to original sources

PubMed2002

Comparison of trough effect of telmisartan vs perindopril using self blood pressure measurement: EVERESTE study.

This multicentre study was aimed at comparing the trough effect of telmisartan and perindopril on diastolic blood pressure (DBP), using self blood pressure measurement (SBPM). A second objective was to compare the data obtained from SBPM with those provided by automatic office BP measurement. A total of 441 mild-to-moderate hypertensive patients were randomised to receive either telmisartan 40 mg or perindopril 4 mg for a period of 12 weeks. Patients whose clinic DBP remained higher than or equal to 90 mmHg at the end of the 6th week (W6) were given a double-dose regimen. Office BP and SBPM were performed at baseline (W0), at W6 and at week 12 (W12), both with the same automatic device. A greater diminution of trough DBP was obtained with telmisartan (-6.6+/-6.7 mmHg) than with perindopril (-5.1+/-7.0 mmHg; P=0.018). Regarding clinic BP, the same results were observed. Doubling dose was significantly less frequent with telmisartan (41%; n=85) than with perindopril (55%; n=115, P=0.005). Mean values of SBPM were lower than office BP values, with a difference of a greater importance at W0 than at W12: 6.6 vs 4.7 mmHg for systolic blood pressure (P<0.005) and 3.2 vs 1.4 mmHg for DBP (P<0.0001). At W12, isolated office hypertension was found in 9% of the patients (n=37), while there were 14% of the patients (n=55) with isolated home hypertension. In conclusion, the trough effect on DBP was statistically higher with telmisartan than with perindopril. SBPM values were lower than office BP values, with greater differences before than after treatment. About a quarter of the patients were found to be controlled with a method but not with the other one.

Adult↗

PubMed1995

Inotropic effects of ouabain and Na, K-ATPase activity in failing rabbit hearts.

Left ventricular (LV) function and Na+, K(+)-ATPase activity were studied in rabbit failing heart (FH) obtained by a double pressure plus volume overload which increased LV/body weight ratio by 58%. Ouabain (10(-6) M) increased peak dP/dt by 69% in control hearts (CH) but not in FH. Na+, K(+)-ATPase activity was similar in FH and in CH but the affinity of Na+, K(+)-ATPase for ouabain was significantly higher in CH than in FH (IC50: 2 microM vs 90 microM). The blunted LV contractile response to ouabain in FH is attributed to a decreased Na+, K(+)-ATPase affinity to ouabain and not to a decreased receptor density.

Animals↗

PubMed1994

Timing and velocity of ejection as major determinants of end-systolic pressure in isolated rabbit hearts.

BACKGROUND: Systolic shortening is known to produce muscle deactivation. The present study was designed to analyze whether the velocity and the timing of ejection play a role on end-systolic pressure-volume relations (ESPVR). METHODS AND RESULTS: In isolated rabbit hearts, left ventricular pressure and volume were recorded and digitized, and left ventricular volume was controlled by a servosystem (4-millisecond cycles) to alter the timing of ejection. A significant deficit in end-systolic pressure was observed when ejection was late in systole with respect to earlier ejection. This was associated with a significantly reduced end-systolic elastance. End-systolic pressure of beats with slow ejection was intermediate between that of the beats with early ejection and that of beats with late ejection with a significantly increased end-systolic volume compared with beats with early rapid ejection. The same results were obtained with hypertrophied hearts (abdominal aortic stenosis). Pressure-volume loop areas were significantly increased in beats with slow ejections and with rapid delayed ejections versus early rapid ejections. No change in the positive peak of dP/dt was observed when the timing and the velocity of ejection were modified. CONCLUSIONS: ESPVR is modified by the ejection profile, with a decreased end-systolic pressure and an increased pressure-volume loop area related to the velocity and the amount of shortening during the end-systolic phase. These indices of ventricular function thus must be used with caution when the timing of ejection is altered, and the end-diastolic volume-peak dP/dt relation may be a better index of ventricular function.

Animals↗

PubMed1994

Sarcoplasmic reticulum function abnormalities in rabbit failing hearts.

In a model of heart failure induced in rabbits by a double volume plus pressure overload, sarcoplasmic reticulum (SR) function was measured by Ca uptake and ryanodine receptor analysis. When expressed per mg of proteins, Ca uptake was decreased by 20% in failing hearts (FH) and ryanodine receptor density was similar in control hearts (CH) and in FH. However Ca uptake and ryanodine receptor density were significantly increased when expressed per total left ventricle suggesting SR hypertrophy. On electron microscopic examination, SR morphology not directly examined but large hypertrophied T tubules were observed suggesting a change in the relationship between membranes and contractile apparatus which may lead to alterations in excitation-contraction-relaxation coupling in spite of minimal biochemical alterations of SR.

Animals↗

PubMed1992

Force-frequency relations and response to ryanodine in failing rabbit hearts.

Force-frequency relations were studied in an isolated-perfused rabbit heart model. Heart failure was induced by a double volume plus pressure overload. Studies were performed at the early stage of heart failure when basal ventricular function was not decreased. The normal positive staircase induced by pacing in control hearts (CH) was replaced by a negative staircase in failing hearts (FH) with an increase in end-diastolic pressure for increased heart rates in FH. Postpacing potentiation and postextrasystolic potentiation (PESP) were significantly reduced in FH as compared with CH. Ventricular function decreased by 60% in both CH and FH under ryanodine with similar dose-response curves. Postpacing and PESP disappeared under ryanodine in CH and in FH with a reversal of the negative staircase in FH. The abnormal force-frequency relations observed in heart failure are thus attributed to sarcoplasmic reticulum dysfunction. Basal ventricular function during spontaneous heart rate may be normal in the early stage of heart failure, but sarcoplasmic reticulum dysfunction produces abnormalities in ventricular function when heart rate is abruptly modified, particularly during tachycardia.

Animals↗

PubMed1991

Increased negative inotropic effect of calcium-channel blockers in hypertrophied and failing rabbit heart.

The effects on ventricular function of calcium channel blockers and isoproterenol were studied in isovolumically beating perfused control rabbit hearts and in hearts subjected to a double pressure plus volume overload studied at the early phase of heart failure. In control hearts, isoproterenol produced an increase of systolic ventricular function and relaxation that was maximal at 10(-7) M. In failing hearts, inotropic state increase in response to isoproterenol was significantly smaller (P less than .01) with no observed lusitropic effect. In control hearts, verapamil and diltiazem produced dose-dependent decreases of ventricular function which were larger with verapamil than with diltiazem (median drug concentration50 of developed pressure was, respectively, 1163 +/- 131 nM and 4524 +/- 451 nM, P less than .001). In failing hearts, contractility decrease was larger than in control hearts (median drug concentration50 of developed pressure was 604 +/- 69 nM and 2691 +/- 580 nM with verapamil and diltiazem, respectively). In contrast, Ro 40-5967, a new calcium-channel blocker, did not produce reductions of inotropic state with concentrations up to 10(-5) M. All three calcium-channel blockers produced a 2-fold increase of coronary flow at 10(-6) M. We conclude that the deleterious effect of verapamil and diltiazem in heart failure is due, at least in part, to a direct depressant effect of these drugs on contractility, which is larger than in control hearts. Additionally, the in vivo sympathetic compensation is probably reduced, as indicated by the decreased ventricular responsiveness to isoproterenol.

Animals↗