Effects of hypoxia on the distribution of calcium in arterial smooth muscle cells of rats and swine

Exposure to hypoxia caused an increase in the hematocrit and right heart weight of experimental rats, but did not affect calcium-45 uptake by pulmonary arterial smooth muscle cells. However, autoradiographic studies showed that hypoxia apparently caused a shift of 45-Ca from primarily extracellular...

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Bibliographic Details
Published inCell and tissue research Vol. 157; no. 1; p. 125
Main Authors Haack, D W, Abel, Jr, J H, Jaenke, R S
Format Journal Article
LanguageEnglish
Published Germany 01.01.1975
Subjects
Animals
Antimony
Autoradiography
Calcium - metabolism
Calcium Radioisotopes
Cytoplasm - metabolism
Extracellular Space
Heart Ventricles
Hematocrit
Hypertension, Pulmonary - etiology
Hypoxia - metabolism
Male
Muscle, Smooth - metabolism
Muscle, Smooth - ultrastructure
Organ Size
Pulmonary Artery - metabolism
Pulmonary Artery - ultrastructure
Rats
Swine
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Summary:Exposure to hypoxia caused an increase in the hematocrit and right heart weight of experimental rats, but did not affect calcium-45 uptake by pulmonary arterial smooth muscle cells. However, autoradiographic studies showed that hypoxia apparently caused a shift of 45-Ca from primarily extracellular sites in arteries of control rats to intracellular sites in tissues of hypertensive rats. Cytochemical studies of calcium distributions in pulmonary arterial smooth muscle cells support the autoradiographic data and show that in both rats and swine the majority of pyroantimonate granules occur extracellulary in control tissues. In contrast, hypoxic tissues displayed a greatly reduced number of granules in extracellular sites and an increase in the amount of precipitate in intracellular sites. In pulmonary arterial smooth muscle cells from hypoxic rats most of the precipitate was associated with the caveolae intracellulares, while in corresponding cells from hypoxic swine in the majority of the pyroantimonate granules were localized to the sarcoplasmic reticulum. Hypoxia may produce pulmonary hypertension by interfering with the ability of the arterial smooth muscle cells to maintain transmembrane ionic gradients, thus producing an effective increase in cytoplasmic calcium levels. The increased calcium may then activate the contractile apparatus to produce a sustained vasoconstriction
ISSN:0302-766X
DOI:10.1007/BF00223235