Effects of left atrial pressure on the pulmonary vascular response to hypoxic ventilation.

We investigated the effects of hypoxic ventilation on the pulmonary arterial pressure- (P) flow (Q) relationship in an intact canine preparation. Mean pulmonary P-Q coordinates were obtained during hypoxic ventilation and during ventilation with 100% O2 at normal and at increased left atrial pressure. Specifically, we tested the hypothesis that, over a wide range, changes in left atrial pressure would alter the effects of hypoxic ventilation on pulmonary P-Q characteristics. Seven dogs were studied. When left atrial pressure was normal (5 mmHg), the mean value of the extrapolated intercept (PI) of the linear P-Q relationship was 10.9 mmHg and the slope (incremental vascular resistance, IR) of the P-Q relationship was 2.2 mmHg.l-1.min. Hypoxic ventilation increased PI to 18 mmHg (P less than 0.01) but did not affect IR. Subsequently, during ventilation with 100% O2, when left atrial pressure was increased to 14 mmHg by inflation of left atrial balloon, PI increased to 18 mmHg. IR was 1.6 mmHg.l-1.min. Again, hypoxic ventilation caused an isolated change in PI. Hypoxia increased PI from 18 to 28 mmHg (P less than 0.01). As in the condition of normal left atrial pressure, hypoxic ventilation did not affect IR. We conclude that, in an anesthetized intact canine preparation, hypoxic ventilation causes an isolated increase in the extrapolated pressure intercept of the pulmonary P-Q relationship. Furthermore the effects of hypoxic ventilation on pulmonary P-Q characteristics are not affected by the resting left atrial pressure.     

Der Einfluß der Tageslänge auf die Knollenbildung der Kartoffel

Zusammenfassung Verkürzung der täglichen Belichtung auf 12 Stunden blieb auf 4 deutsche Kartoffelsorten, abgesehen von einigen morphologischen Veränderungen, ohne Einfluß. Bei 3 verschiedenen südamerikanischen Kulturkartoffeln zeigte sich eine außerordentliche Steigerung der Erträge, Verminderung der Wurzelmasse und Verkürzung der Stolonen. Diese Ergebnisse werden in Beziehung gebracht zu den Ergebnissen anderer Autoren bei ähnlichen Versuchen mit Kartoffeln und anderen Objekten.     

Referate

Ohne Zusammenfassung