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P Jouannot

Publications and source records attributed to P Jouannot.

22 records · Page 2Linked to original sources
PubMedDate not supplied

Pulsus alternans in regionally hypoxic ventricles of open-chest dogs: regional mechanical alternation of potentiation and attenuation of the inotropic state.

Sustained mechanical alternation appeared after a spontaneous premature ventricular contraction in 6 open-chest dogs during the perfusion of the left circumflex coronary artery by Krebs-Henseleit solution equilibrated with 5% CO2 and 95% N2. The animals were instrumented with a catheter in the left ventricle and ultrasonic crystals in hypoxic and control segments. Left ventricular systolic pressure was significantly higher in the strong than in the weak beats with no significant difference of end-diastolic lengths in hypoxic and control segments. In hypoxic segments, systolic shortening was significantly larger in strong beats (11.9 +/- 1.9%) as compared with weak beats (5.1 +/- 1.6%) and with control beats preceding the premature ventricular contraction (9.7 +/- 1.6%) but the postextrasystolic beat was larger (17.9 +/- 1.3%). There was no significant change of systolic shortening in control segments during mechanical alternation which appears thus as a regional phenomenon which cannot be explained by the Starling mechanism: instead, alternation is attributed to a change of excitation-contraction coupling after a premature contraction with alternation of potentiation and attenuation of the inotropic state.

Animals↗
PubMedDate not supplied

[VO2 max: technique and practical importance].

NORMAL SITUATION: Ergonometric spirometric measurement of O2 consumption and CO2 production (VO2max) can be used to assess adaptation of the oxygen transportation system to exercise. In the normal situation, the capacity to sustain exertion in everyday physical activities depends directly on the capacity of this system to adapt, i.e. the level of physical training. PATHOLOGICAL CONDITIONS: In diseased patients, this test can measure the degree of non-adaptation and the efficacy of compensatory mechanism of the oxygen transport system. It can be used as a pathophysiological diagnostic tool for following divers disease states, particularly heart conditions. Spirometry is a key test used in all cardiology centers to assess the degree of heart failure.

Adolescent↗
PubMedDate not supplied

[The left ventricle at different stages of a two steps mechanical overloading. Electron microscopic study in the rat (author's transl)].

The left ventricle myocardium of rats subjected to a two steps mechanical overloading (abdominal aorta constriction + aortic insufficiency) was examined in the light and electron microscopes at several stages of the load, and particularly after 3 to 6 months when the animals exhibited congestive heart failure. In these conditions, the heart weight exceeded the control by more than 100%. In the later stages, the absence of parallelism between heart weight and cell diameter was compatible with a process of hyperplasia. Cellular lesions looking like recent were found more and more frequently with time. Within apparently normal cells proliferation of small mitochondria, nucleoli and Golgi apparatus are compatible with some deficit in energy balance, which is usually encountered only in early stages of the load.

Animals↗