[Misrodissection study of the distribution and length of the proximal tubules of the kidney of five species of rodents].
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Biomedical subjects
Publications and source records attributed to F Morel.
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Adenylate-cyclase (AC) activity measurements were performed in the different segments of the mouse nephron. It was found that: --the medullary portion of the thick ascending limb is sensitive to AVP alone. --Three hormones, parathyroid hormone, calcitonin and isoproterenol, stimulate the enzyme activity located in the "bright" and "granular" portions of the distal convoluted tubule. The "granular" portion is, in addition, sensitive to AVP. --a single type of collecting tubules is present and every distal convoluted tubule is connected to it. In the cortex, this collecting segment is sensitive to AVP, calcitonin and isoproterenol. In the medulla, it is sensitive to AVP alone. The enzyme sensitivity to hormones was found in the mouse to be different from that previously described in the rabbit; this is particularly true for the distal segments of the nephron. Thus, hormonal segmentation and more over, regulation of physiological function may be different from one species to another.
The zinc metalloproteinases (MMPs or matrixins) are capable of damaging most of the constituents of the extra-cellular matrix and the basement membrane. The matrix proteolysis is the result of an imbalance both in the turnover of these constituants and in the ratio of the tissue inhibitors of metalloproteinases (TIMPs) versus metalloproteinases. After a brief description of the nature and structure of MMPs and TIMPs, this article reports on recent progress concerning the intra and extra-cellular activation mechanisms of proenzymes (proMMPs) which bring into play a series of proteolytic activations involving different proteinase families. Two points are stressed: 1) the main sites of focalized matrix proteolysis regulation, illustrated in the cellular interaction of inflammation, and 2) the wide phenotypic variety of MMPs and TIMPs.