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M Gagnan-Brunette

Publications and source records attributed to M Gagnan-Brunette.

9 recordsLinked to original sources
PubMed1980

Adenylate cyclase responsiveness to hormones in various portions of the human nephron.

The action sites for parathyroid hormone (PTH), salmon calcitonin (SCT), and arginine-vasopressin (AVP) were investigated along the human nephron by measuring adenylate cyclase activity, using a single tubule in vitro microassay. Well-localized segments of tubule were isolated by microdissection from five human kidneys unsuitable for transplantation. PTH (10 IU/ml) increased adenylate cyclase activity in the convoluted and the straight proximal tubule, in the medullary and cortical portions of the thick ascending limb, and in the early portion of the distal convoluted tubule (corresponding stimulated:basal activity ratios were 64, 19, 10, 18, and 22, respectively). SCT (10 ng/ml) increased adenylate cyclase activity in the medullary and cortical portions of the thick ascending limb, in the early portion of the distal convoluted tubule, and, to a lesser extent, in the cortical and the medullay collecting tubule (activity ratios were 7, 14, 15, 3, and 3, respectively). AVP (1 microM) stimulated adenylate cyclase activity in the terminal nephron segments only, i.e., the late portion of the distal convoluted tubule, the cortical and medullary portions of the collecting tubule (activity ratios 81, 51, and 97, respectively). As measured in one experiment, nearly one-half maximal responses were obtained with 0.1 IU/ml PTH or 0.3 ng/ml SCT in thick ascending limbs and with 1 nM AVP in collecting tubules, suggesting that enzyme sensitivity to hormones as well preserved under the conditions used in this study.

Adenylyl Cyclases↗
PubMed1977

Compensatory renal hypertrophy in dogs: single nephron glomerular filtration rate.

Sodium ferrocyanide was used to measure the intrarenal distribution of single nephron glomerular filtration rate (SNGFR) in remaining kidneys of dogs, 10 d after contralateral nephrectomy. It was first demonstrated that the renal function of both kidneys in situ was comparable. Following right nephrectomy, the urine volume, p-aminohippuric acid clearance, creatine clearance, osmolar clearance, fractional excretion of potassium, and sodium excretion of the left kidney increased. Fractional excretion of sodium, free water clearance, and filtration fraction remained unchanged. Following that 10-d period, left kidney weight exceeded that of the previously removed contralateral kidney by 50%, indicating that most of the compensatory hypertrophy had already occurred. No significant difference in the length of the proximal tubule nor in the diameter of the glomeruli of superficial (SUP) and juxtamedullary (JM) nephrons of either kidney could be demonstrated. Most importantly, the ratio of radioactivity in the SUP/JM nephrons of the residual kidney was comparable with that previously observed in normal dog kidneys. Thus, the increase in total kidney GFR is explained through a proportional increase in the SNGFR of the SUP and JM nephrons.

Animals↗
PubMedDate not supplied

Different hormonal target sites along the mouse and rabbit nephrons.

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.

Adenylyl Cyclases↗