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Electron microscopic cytochemical localization of Ca-ATPase in toad urinary bladder
Summary
Calcium adenosine triphosphatase (Ca-ATPase) in amphibian urinary bladder epithelium is localized to the basolateral border and mitochondria. Antidiuretic hormone (ADH) enhances Ca-ATPase activity, suggesting a role in regulating cytosolic calcium.
Area of Science:
- Cell Biology
- Biochemistry
- Physiology
Background:
- The amphibian urinary bladder plays a crucial role in water and ion transport.
- Calcium-regulating enzymes are vital for cellular homeostasis and signaling.
Purpose of the Study:
- To localize the calcium-regulating enzyme calcium adenosine triphosphatase (Ca-ATPase) in amphibian urinary bladder epithelium.
- To investigate the effect of antidiuretic hormone (ADH) on Ca-ATPase activity.
Main Methods:
- One-step electron microscopic cytochemical procedure.
- Incubation in various media (substrate-free, calcium-free, magnesium-substituted) and with vanadate.
- Treatment with antidiuretic hormone (ADH; vasopressin).
Main Results:
- Ca-ATPase activity was localized to the basolateral plasmalemmae of epithelial cells and the mitochondrial matrix of mitochondria-rich cells.
- Enzyme activity was dependent on substrate and calcium, and enhanced by magnesium substitution.
- ADH (vasopressin) significantly increased both basolateral and mitochondrial Ca-ATPase reactions.
Conclusions:
- Ca-ATPase is strategically located in the amphibian urinary bladder epithelium to regulate calcium transport.
- ADH influences Ca-ATPase activity, indicating its involvement in the hormone's effect on cytosolic calcium concentration.