What question did this study set out to answer?

Determine the mechanisms driving urinary acidification and assess the role of transepithelial potential difference in cortical versus medullary collecting tubules.

December 1, 1983Journal of Clinical InvestigationOpen Access

Characterization of acidification in the cortical and medullary collecting tubule of the rabbit.

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Determine the mechanisms driving urinary acidification and assess the role of transepithelial potential difference in cortical versus medullary collecting tubules.
Isolated and microperfused cortical and medullary collecting tubules obtained from starved New Zealand white rabbits.
Measured total CO2 flux using microcalorimetry and recorded transepithelial potential difference under symmetric bath and luminal conditions containing 25 meq bicarbonate bubbled with 93.3% O2 and 6.7% CO2.
Assessed tubular responses to the addition of ouabain (10⁻⁸ M and 10⁻⁴ M) and the substitution of 40 mM NaCl with 40 mM LiCl.
In cortical collecting tubules, bath addition of 10⁻⁸ M ouabain significantly reduced transepithelial potential difference from -16.4 to -2.2 mV (P < 0.001) and total CO2 flux from +6.0 to 1.5 pmol/mm per min (P < 0.005), whereas medullary tubules showed no change in either parameter.
Substitution with 40 mM LiCl in cortical tubules decreased potential difference from -11.6 to 0.4 mV (P < 0.005) and total CO2 flux from +10.8 to +4.2 pmol/mm per min (P < 0.025), with no observable effect in medullary tubules.
Baseline total CO2 flux correlated inversely with animal bladder urine pH in both tubule segments, with medullary collecting tubules exhibiting higher flux rates than cortical tubules.

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Implication

Ex vivo microperfusion study reveals distinct potential-dependent acidification in rabbit collecting tubules, indicating segment-specific adaptations during starvation.

Cite This Study

Laski et al. (1983) studied this question.

synapsesocial.com/papers/6aa8861f2badce9cdeb43f94 https://doi.org/10.1172/jci111170

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Implication

Ex vivo microperfusion study reveals distinct potential-dependent acidification in rabbit collecting tubules, indicating segment-specific adaptations during starvation.

Characterization of acidification in the cortical and medullary collecting tubule of the rabbit.

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Discussion

Implication

Cite This Study

Characterization of acidification in the cortical and medullary collecting tubule of the rabbit.

Key Points

Discussion

Implication

Cite This Study

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