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2. Effect of prenatal hypoxia on contractile performance and responsiveness to Ca2+ in the isolated perinatal rat heart
- Creator:
- Ošťádalová, I., Ošťádal, B., and Kolář, F.
- Type:
- article, model:article, and TEXT
- Subject:
- prenatal hypoxia, cardiac contractility, ontogenetic development, and calcium
- Language:
- English
- Description:
- The effect of prenatal hypoxic stress on the cardiac contractile function and responsiveness to calcium was studied in rats during the perinatal period. Pregnant rats were exposed to intermittent high altitude hypoxia from day 14 to 18 of pregnancy. Foetal hearts (prenatal day 22) and the hearts of offsprings (days 1, 4 and 7) were isolated and perfused in the Langendorff mode. Developed force of contraction (DF) as well as the rate of force development and fall were measured a) at the Ca2+ concentration of 1.25 mmol.l-1, b) under increasing Ca2+ concentration (from 0.6 to 10.0 mmol.l-1). Body and heart weights were significantly smaller in hypoxic than in matched control rats starting from day 1. The contractile performance of hypoxic hearts did not differ from controls. Their inotropic response to increasing Ca2+ concentrations was, however, significantly reduced on prenatal day 22 and postnatal day 7. Our results suggest that prenatal maternal hypoxia affects the cardiac inotropic responsiveness to Ca2+ even postnatally.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3. Low Body Weight and Cardiac Tolerance to Ischemia in Neonatal Rats
- Creator:
- Chvojková, Z., Ošťádalová, I., and Ošťádal, B.
- Type:
- article, model:article, and TEXT
- Subject:
- High altitude hypoxia, Low body weight, Cardiac tolerance to ischemia, and Neonatal rats
- Language:
- English
- Description:
- Adaptation to intermittent high altitude hypoxia (IHAH) increases tolerance of the isolated neonatal rat heart to ischemia and potentiates protection induced by ischemic preconditioning. In addition to the protective effect, IHAH significantly reduces growth of the animals. The aim of the present study was, therefore, to find out whether low body weight per se might influence cardiac sensitivity to oxygen deprivation. Low body weight was induced either by IHAH (barochamber, 8 h/day, 5000 m) from postnatal day 1 to 10 (HLBW), or by a higher number of sucklings per mother (14 instead of 8), again from postnatal day 1 to 10 (NLBW). Control animals (8 littermates per mother) were kept under normoxic conditions (Controls). The recovery of developed force following 40 min of global ischemia was measured in isolated hearts from 10-day-old rats by perfusing them in the Langendorff mode with Krebs-Henseleit solution at constant pressure, temperature and rate. Ischemic preconditioning was induced by three 3-min periods of global ischemia, each separated by 5-min periods of reperfusion. Low body weight in HLBW and NLBW groups was accompanied by increased hematocrit, and decrease in absolute heart weight (both wet and dry) and developed force. On the other hand, higher hydration, increased cardiac tolerance to ischemia and potentiation of protection by ischemic preconditioning were observed in HLBW rats only. This experimental group also exhibited the highest relative heart weight. It may be concluded that low body weight alone does not influence cardiac tolerance to ischemia in neonatal rats.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public