Showing papers by "Ulf Ekelund published in 2000"

cGMP-independent inotropic effects of nitric oxide and peroxynitrite donors: potential role for nitrosylation.

Abstract: Nitric oxide (NO) has concentration-dependent biphasic myocardial contractile effects. We tested the hypothesis, in isolated rat hearts, that NO cardiostimulation is primarily non-cGMP dependent. Infusion of 3-morpholinosydnonimine (SIN-1, 10(-5) M), which may participate in S-nitrosylation (S-NO) via peroxynitrite formation, increased the rate of left ventricular pressure rise (+dP/dt; 19 +/- 4%, P < 0.001, n = 11) without increasing effluent cGMP or cAMP. Superoxide dismutase (SOD; 150 U/ml) blocked SIN-1 cardiostimulation and led to cGMP elaboration. Sodium nitroprusside (10(-10)-10(-7) M), an iron nitrosyl compound, did not augment +dP/dt but increased cGMP approximately eightfold (P < 0.001), whereas diethylamine/NO (DEA/NO; 10(-7) M), a spontaneous NO. donor, increased +dP/dt (5 +/- 2%, P < 0.05, n = 6) without augmenting cGMP. SIN-1 and DEA/NO +dP/dt increase persisted despite guanylyl cyclase inhibition with 1H-(1,2,4)oxadiazolo-(4,3,-a)quinoxalin-1-one (10(-5) M, P < 0.05 for both donors), suggesting a cGMP-independent mechanism. Glutathione (5 x 10(-4) M, n = 15) prevented SIN-1 cardiostimulation, suggesting S-NO formation. SIN-1 also produced SOD-inhibitable cardiostimulation in vivo in mice. Thus peroxynitrite and NO donors can stimulate myocardial contractility independently of guanylyl cyclase activation, suggesting a role for S-NO reactions in NO/peroxynitrite-positive inotropic effects in intact hearts.

Improved Mechanoenergetics and Cardiac Rest and Reserve Function of In Vivo Failing Heart by Calcium Sensitizer EMD-57033

Abstract: Background—Myofilament Ca2+ sensitizers enhance contractility but can adversely alter diastolic function through sensitization to low intracellular Ca2+ concentration. Concomitant phosphodiesterase III inhibition (PDE3I) may offset diastolic changes but limit the mechanoenergetic benefits. We tested whether selective Ca2+ sensitization in vivo with the use of EMD-57033 enhances both systolic and diastolic function in failing hearts at minimal energetic cost. Methods and Results—Pressure-dimension data were measured with sonomicrometry/micromanometry in conscious dogs before (CON, n=9) and after tachycardia-induced heart failure (HF, n=11). In contrast to blunted dobutamine (DOB) responses in HF, low-dose EMD-57033 (0.4 mg · kg−1 · min−1 for 20 minutes) markedly enhanced contractility, doubling end-systolic elastance and raising fractional shortening similarly in CON-treated and HF hearts. EMD-57033 effects were achieved at a reduced heart rate, without vasodilation. EMD-57033 augmented blunted heart rate-...

Field evaluation of the Computer Science and Application's Inc. Activity monitor during running and skating training in adolescent athletes

Abstract: This study investigated the validity of the CSA activity monitor for assessment of the total amount of physical activity in adolescent athletes. Activity data were compared to data on daily energy ...

Total daily energy expenditure and pattern of physical activity measured by minute-by-minute heart rate monitoring in 14–15 year old Swedish adolescents

Abstract: OBJECTIVE: To assess total daily energy expenditure (TDEE) and patterns of physical activity among Swedish male and female adolescents and to relate the amount and intensity of physical activity to ...

Relative contribution of preload and afterload to the reduction in cardiac output caused by nitric oxide synthase inhibition with L-N(G)-methylarginine hydrochloride 546C88.

Abstract: OBJECTIVE: The nitric oxide synthase inhibitor L-N(G)-methylarginine hydrochloride (L-NMMA HC1 546C88) causes reductions in cardiac output (CO), a potential limitation to clinical application. This drop in CO exceeds that from phenylephrine at matched systemic arterial pressure. We tested the hypothesis that the greater fall in CO attributable to L-NMMA primarily reflects a difference in venoconstriction between agents, such that phenylephrine produces larger increases in preload (an independent determinant of CO). DESIGN: Random infusion of phenylephrine or L-NMMA. SETTING: An animal research laboratory. SUBJECTS: Eight healthy, conscious, male dogs. INTERVENTIONS: L-N(G)-methylarginine hydrochloride (20 mg/kg for 1 hr) and phenylephrine (0.5 to 3 microg/kg/min) were administered into eight dogs chronically instrumented to measure left ventricular pressure and dimension. Data were measured at a constant heart rate (140 beats/min) to render CO proportional to stroke dimension. MEASUREMENTS AND MAIN RESULTS: At a matched increase in afterload (effective arterial elastance), L-NMMA increased preload (end-diastolic dimension) to a lesser degree (3.8%+/-1.5%, p < .05) than phenylephrine (9.6%+/-1.6%, p < .05 vs. L-NMMA). Neither L-NMMA nor phenylephrine affected the slope of the end-systolic pressure dimension relationship, although L-NMMA shifted the relationship rightward (1.7+/-0.7 mm, p < .05), consistent with a mild negative inotropic effect. L-NMMA decreased the stroke dimension to a greater extent than phenylephrine (-24.1%+/-6.8% and -10.6%+/-3.4%, respectively, p < .05). CONCLUSIONS: Differential CO responses to phenylephrine and L-NMMA were primarily attributable to changes in preload. Variable venular vs. arteriolar constrictor effects must be considered when evaluating the integrated cardiovascular response to a vasoactive agent. (Less)

Hur aktiva är våra barn och ungdomar

Abstract: Massmedia har pa senare ar gett en bild av att barn och ungdomar tillbringar en stor del av sin tid stillasittande. Graden av fysisk aktivitet sags ha sjunkit och andelen barn och ungdomar med over ...

European Master's in Public Health Nutrition : Folkhälsovetenskap, Nutrition och Fysisk Aktivitet i kombination med Europadimension

Abstract: European Master's in Public Health Nutrition : Folkhalsovetenskap, Nutrition och Fysisk Aktivitet i kombination med Europadimension