title: Evidence for a direct action of insulin to increase renal reabsorption of calcium and for an irreversible defect in renal ability to conserve calcium due to prolonged absence of insulin.
abstract: Male rats were injected with streptozotocin (STZ), 60 mg/kg, i.p., on 2 successive days. Six hours after the last STZ injection, some STZ-diabetic rats began receiving daily injections of insulin that were insufficient to control blood glucose. Another group of STZ-diabetic rats received insulin injections after 2 wk duration of untreated diabetes. Still other STZ-diabetic rats received no insulin treatment. Under sodium pentobarbital anesthesia, kidneys from each treatment group were isolated and perfused with an artificial "plasma" containing 45Ca. As urine was collected, urine-to-perfusate ultrafiltrate (U/P) ratios for 45Ca were determined. The results of the studies showed that: STZ diabetes reduced 45Ca reabsorption by the kidney; the increased urinary excretion of calcium was not due to an osmotic effect or to a direct nephrotoxic action of STZ; and insulin therapy instituted early, but insufficient to control blood glucose, reduced the diabetes-induced calcium loss via a direct action on the kidney, whereas insulin therapy instituted late failed to reverse renal loss of calcium.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism; D005919:Glomerular Filtration Rate / Q000187:drug effects; D005947:Glucose / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology* / Q000502:physiology; D007668:Kidney / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D007328:Insulin; D005947:Glucose; D002118:Calcium