rdf:type |
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lifeskim:mentions |
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pubmed:issue |
11
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pubmed:dateCreated |
1997-1-23
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pubmed:abstractText |
Experiments were performed to test the hypothesis that diabetes mellitus is associated with impaired afferent arteriolar responsiveness to opening of voltage-gated calcium channels. Diabetes was induced by injection of streptozocin (65 mg/kg, i.v.) and insulin was administered via an osmotic minipump to achieve moderate hyperglycemia. Sham rats received vehicle treatments. 2 wk later, the in vitro blood-perfused juxtamedullary nephron technique was used to allow videomicroscopic measurement of afferent arteriolar contractile responses to increasing bath concentrations of either Bay K 8644 or K+. Baseline afferent arteriolar diameter in kidneys from diabetic rats (26.4+/-1.2 microm) exceeded that of Sham rats (19.7+/-1.0 microm). Bay K 8644 evoked concentration-dependent reductions in afferent diameter in both groups of kidneys; however, arterioles from Sham rats responded to 1 nM Bay K 8644 while 100 nM Bay K 8644 was required to contract arterioles from diabetic rats. The EC50 for K+-induced reductions in afferent arteriolar diameter was greater in diabetic kidneys (40+/-4 mM) than in kidneys from Sham rats (28+/-4 mM; P < 0.05). In afferent arterioles isolated by microdissection from Sham rats and loaded with fura 2, increasing bath [K+] from 5 to 40 mM evoked a 98+/-12 nM increase in intracellular Ca2+ concentration ([Ca2+]i). [Ca2+]i responses to 40 mM K+ were suppressed in afferent arterioles from diabetic rats (delta = 63+/-5 nM), but were normalized by decreasing bath glucose concentration from 20 to 5 mM. These observations indicate that the early stage of insulin-dependent diabetes mellitus is associated with a functional defect in afferent arteriolar L-type calcium channels, an effect which may contribute to suppressed afferent arteriolar vasoconstrictor responsiveness and promote glomerular hyperfiltration.
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pubmed:commentsCorrections |
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pubmed:language |
eng
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pubmed:journal |
|
pubmed:citationSubset |
AIM
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pubmed:chemical |
|
pubmed:status |
MEDLINE
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pubmed:month |
Dec
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pubmed:issn |
0021-9738
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pubmed:author |
|
pubmed:issnType |
Print
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pubmed:day |
1
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pubmed:volume |
98
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
2564-71
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pubmed:dateRevised |
2009-11-18
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pubmed:meshHeading |
pubmed-meshheading:8958219-Animals,
pubmed-meshheading:8958219-Potassium,
pubmed-meshheading:8958219-Kidney,
pubmed-meshheading:8958219-Diabetes Mellitus, Experimental,
pubmed-meshheading:8958219-Glucose,
pubmed-meshheading:8958219-Calcium,
pubmed-meshheading:8958219-Rats,
pubmed-meshheading:8958219-Male,
pubmed-meshheading:8958219-Kinetics,
pubmed-meshheading:8958219-Renal Circulation,
pubmed-meshheading:8958219-Nephrons,
pubmed-meshheading:8958219-Glomerular Filtration Rate,
pubmed-meshheading:8958219-Arterioles,
pubmed-meshheading:8958219-Rats, Sprague-Dawley,
pubmed-meshheading:8958219-Muscle, Smooth, Vascular,
pubmed-meshheading:8958219-Calcium Channels
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