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Variability of cellular responsiveness to ADH stimulation in toad urinary bladder
W A Kachadorian1, J Muller, V A DiScala
1Laboratory of Cardiovascular Science, National Institute on Aging, Baltimore 21224.
The American Journal of Physiology
|April 1, 1989
Summary
Individual toad bladder cells show varied responses to antidiuretic hormone (ADH). This cellular heterogeneity influences the overall tissue
Area of Science:
- Cell biology
- Physiology
- Membrane biophysics
Background:
- Antidiuretic hormone (ADH) regulates water balance by acting on kidney collecting ducts.
- The hydrosmotic response involves changes in the luminal membrane of granular cells.
- Morphological changes, like particle aggregation, serve as indicators of cellular activation.
Purpose of the Study:
- To quantify individual cell variability in response to maximal antidiuretic hormone (ADH) stimulation.
- To compare cellular response patterns in tissues with maximal versus submaximal overall stimulation.
- To investigate the nature of cellular participation in the hydrosmotic response.
Main Methods:
- Utilized morphological indexes of hormonally induced cell activation in toad bladder granular cells.
- Assessed fusion of aggrephores and appearance of intramembrane particle aggregates in the luminal membrane.
- Compared cellular responses in paired tissues with varying levels of transtissue water flow.
Main Results:
- Individual cell responsiveness to maximal ADH treatment varied two- to sevenfold.
- This variability suggests inherent heterogeneity in granular cell reactivity to ADH.
- Cellular responses to ADH appear to be graded, not all-or-none, based on aggregate incidence.
Conclusions:
- Significant variability exists in individual granular cell responsiveness to ADH.
- Inherent cellular heterogeneity contributes to the observed response variations.
- Granular cells participate in a graded manner in the hydrosmotic response, irrespective of their sensitivity.