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PMID |
Sentence |
1 |
1716061
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One of the mechanisms by which Li evokes polyuria is thought to be impairment of arginine vasopressin (AVP)-sensitive adenylate cyclase (AdC) in cells of the renal collecting duct.
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2 |
1716061
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To investigate how AdC is influenced by chronic administration of Li, we created nephrogenic diabetes insipidus (NDI) in rats and microdissected the medullary collecting tubule from both control and NDI rats.
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3 |
1716061
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One of the mechanisms by which Li evokes polyuria is thought to be impairment of arginine vasopressin (AVP)-sensitive adenylate cyclase (AdC) in cells of the renal collecting duct.
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4 |
1716061
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To investigate how AdC is influenced by chronic administration of Li, we created nephrogenic diabetes insipidus (NDI) in rats and microdissected the medullary collecting tubule from both control and NDI rats.
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5 |
2989335
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Medullary collecting tubules (MCT) and papillary collecting ducts (PCD) microdissected from Li-treated animals had higher content of protein than MCT and PCD from the control rats.
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6 |
2989335
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Also, the cAMP accumulation in MCT and PCD after incubation with forskolin was markedly lower in Li-treated rats.
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7 |
2989335
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The activity of adenylate cyclase (AdC) in MCT of Li-treated rats, both the basal and the activity stimulated by AVP, forskolin, or fluoride, was significantly (delta approximately equal to -30%) reduced, while the activity of cAMP phosphodiesterase (cAMP-PDIE) in the same segment showed no significant difference from the controls.
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8 |
2989335
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In MCT of control rats, the rate of [14C]succinate oxidation was approximately 3 times lower than in MAL.
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9 |
2989335
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Based on these results, we conclude that at least two factors play an important role in the pathogenesis of NDI consequent to chronic oral administration of Li: (a) decreased ability of MCT and PCD to generate and accumulate cAMP in response to stimulation by AVP; this defect is primarily due to diminished activity of AdC in these tubular segments caused by prolonged exposure to Li; and (b) lower osmolality of renal papillary tissue, due to primarily to depletion of urea, which decreases osmotic driving force for water reabsorption in collecting tubules.
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10 |
2989335
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Medullary collecting tubules (MCT) and papillary collecting ducts (PCD) microdissected from Li-treated animals had higher content of protein than MCT and PCD from the control rats.
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11 |
2989335
|
Also, the cAMP accumulation in MCT and PCD after incubation with forskolin was markedly lower in Li-treated rats.
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12 |
2989335
|
The activity of adenylate cyclase (AdC) in MCT of Li-treated rats, both the basal and the activity stimulated by AVP, forskolin, or fluoride, was significantly (delta approximately equal to -30%) reduced, while the activity of cAMP phosphodiesterase (cAMP-PDIE) in the same segment showed no significant difference from the controls.
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13 |
2989335
|
In MCT of control rats, the rate of [14C]succinate oxidation was approximately 3 times lower than in MAL.
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14 |
2989335
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Based on these results, we conclude that at least two factors play an important role in the pathogenesis of NDI consequent to chronic oral administration of Li: (a) decreased ability of MCT and PCD to generate and accumulate cAMP in response to stimulation by AVP; this defect is primarily due to diminished activity of AdC in these tubular segments caused by prolonged exposure to Li; and (b) lower osmolality of renal papillary tissue, due to primarily to depletion of urea, which decreases osmotic driving force for water reabsorption in collecting tubules.
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15 |
16825029
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This amino acid is a substrate for at least 5 enzymes identified in mammals, including arginase, arginine-glycine transaminase, kyotorphine synthase, nitric oxide synthase, and arginine decarboxylase.
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