title: Further evidence of an intravesicular Ca2+- pump in odontoblasts from rat incisors.
abstract: Intracellular vesicles containing alkaline phosphatases were isolated from isolated odontoblasts using several centrifugation techniques, gradient media and filtering procedures. With a combined centrifugation technique using 0.32 M sucrose layered on 1.23 M sucrose, a fraction containing alkaline phosphatases with a 36-40-fold increased specific activity was obtained. This fraction also revealed a high Ca2+-accumulating ability. The vesicle fraction was totally free from mitochondria but to some extent contaminated by lysosomes. Characteristics of Ca2+-uptake were obtained. The Ca2+-uptake was maximal at 37-40 degrees C whereas no Ca2+-accumulated at 4 degrees C. Temperatures above 40 degrees C strongly inhibited Ca2+-uptake. ATP was the most potent stimulator of Ca2+-uptake whereas ITP, GTP, CTP, ADP, PPi and AMP also promoted Ca2+-uptake. Cysteine, EDTA and Triton X-100 were inhibitory to Ca2+-uptake. A correlation between alkaline phosphatases in intracellular vesicles as well as their relation to extracellular matrix vesicles and to the mineralization process is suggested.
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D004247:DNA; D007180:Incisor; D008297:Male; D009804:Odontoblasts / Q000378:metabolism*; D009940:Organoids / Q000378:metabolism; D012313:RNA; D051381:Rats; D011919:Rats, Inbred Strains; D013696:Temperature
chemical_list: D012313:RNA; D004247:DNA; D000469:Alkaline Phosphatase; D000252:Calcium-Transporting ATPases; D002118:Calcium