Developmental changes of Ca++ transport systems in chick heart.
Sarcolemma (SL) Na+/Ca++ exchange, binding of the Ca++ channel antagonist [3H]nitrendipine and sarcoplasmic reticulum (SR) Ca++ uptake were studied in crude membranes from developing chick heart. Energy-linked Ca++ uptake of mitochondria (MT) was measured in tissue homogenates. When reckoned per unit of heart mass Na+/Ca++ exchange increases linearly (20-fold) from embryonic day 4 to postnatal day 10. These changes correlate strongly with developmental variations of (Na+, K+)ATPase activity. The density of high-affinity [3H]nitrendipine receptors increases in parallel, while the specific affinity does not change SR Ca++ uptake rises steadily during embryogenesis and increases steeply (3-fold) at the time of hatching. Hearts of 10-day-old chickens exhibit 50-fold higher SR Ca++ transport activities than those of 4-day-old embryos. Between the latter stage and postnatal day 10 a more than 100-fold increase of MT Ca++ uptake occurs. The results suggest developmental variations in the contribution of single Ca++ transporting systems in cardiac Ca++ control.
D000367:Age Factors; D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D002642:Chick Embryo; D006321:Heart / Q000196:embryology*; D008929:Mitochondria, Heart / Q000378:metabolism; D009543:Nifedipine / Q000031:analogs & derivatives / Q000378:metabolism; D009568:Nitrendipine; D012508:Sarcolemma / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D009568:Nitrendipine; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D009543:Nifedipine; D002118:Calcium