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Published on: September 1, 2016
Thiazide treatment of rats provokes apoptosis in distal tubule cells
J Loffing1, D Loffing-Cueni, I Hegyi
1Institute of Anatomy, University of Zurich, Switzerland.
Abstract:
We studied the effects of inhibition of apical NaCl entry on the structural correlates for electrolyte transport in the distal convoluted tubule (DCT) of rats. Thiazide diuretics were used to block NaCl entry specifically in the DCT. Metolazone or hydrochlorothiazide (HCTZ) were applied for three days subcutaneously via osmotic minipumps. The renal epithelial structure of control and treated rats was studied by light and electron microscopy. Distribution of the thiazide-sensitive NaCl cotransporter (rTSC1), calbindin D28K and Ca(2+)-Mg(2+)-ATPase was examined by immunohistochemistry, and the content of rTSC1 transcripts by Northern blot and in situ hybridization. In treated rats the DCT epithelium had lost the structural characteristics of electrolyte transporting epithelia and the cells were in different stages of apoptosis. In damaged cells calbindin D28K and Ca(2+)-Mg(2+)-ATPase were strongly decreased; the rTSC1 was shifted from the luminal membrane to the basal cell half and was found additionally in small membrane vesicles in intercellular and peritubular spaces. Transcripts of rTSC1 were drastically reduced in homogenates of kidney cortex and almost absent in damaged DCT cells. All other tubular segments were unaffected by the treatment. Focal inflammatory infiltrates were found to be specifically surrounding DCT profiles. Thus, inhibition by thiazides of apical NaCl entry into DCT cells is associated with apoptosis of DCT cells and focal peritubular inflammation.
Insights
Thiazide diuretics cause apoptosis in rat distal convoluted tubule cells by blocking NaCl entry. This leads to cellular damage, reduced transporter expression, and inflammation in kidney tissue.
Area of Science:
- Nephrology
- Cell Biology
- Pharmacology
Background:
- The distal convoluted tubule (DCT) is crucial for electrolyte balance.
- Thiazide diuretics inhibit NaCl transport in the DCT.
- Understanding the cellular effects of thiazides is important for kidney physiology.
Purpose of the Study:
- To investigate the structural changes in the DCT following inhibition of apical NaCl entry.
- To examine the impact of thiazides on key proteins and transcripts in DCT cells.
- To determine the relationship between thiazide treatment and renal inflammation.
Main Methods:
- Rats were treated with metolazone or hydrochlorothiazide (HCTZ) via osmotic minipumps for three days.
- Renal tissues were analyzed using light and electron microscopy.
- Immunohistochemistry, Northern blot, and in situ hybridization were employed to assess protein and transcript levels.
Main Results:
- Thiazide treatment resulted in the loss of electrolyte transport characteristics in DCT epithelium.
- Affected DCT cells showed signs of apoptosis, with decreased calbindin D28K and Ca(2+)-Mg(2+)-ATPase.
- The thiazide-sensitive NaCl cotransporter (rTSC1) localization changed, and its transcripts were significantly reduced.
- Focal inflammatory infiltrates were observed around DCT profiles, while other kidney segments remained unaffected.
Conclusions:
- Inhibition of apical NaCl entry by thiazides induces apoptosis in DCT cells.
- Thiazide treatment disrupts DCT cell structure and function.
- Apoptosis and altered transporter expression in DCT cells are associated with focal peritubular inflammation.
