title: Single nephron function of the lesser spotted dogfish, Scyliorhinus canicula, and the effects of adrenaline.
abstract: Function of the kidney and the nephron in the lesser spotted dogfish, Scyliorhinus canicula, was investigated by clearance, renal tubular micropuncture and ferrocyanide infusion techniques. 70% of the glomerular filtrate was reabsorbed within the renal tubule, producing slightly hypotonic urine. Glomeruli were: perfused and filtering (F); arterially perfused but not filtering (NF); or non-arterially perfused and hence not filtering (NP). Adrenaline reduced the proportion of filtering glomeruli from 94% to 70%. Despite this reduction, a marked overall glomerular diuresis occurred. Single nephron glomerular filtration rates (SNGFRs) ranged from 1.5 to 26 nl min-1 with a mean rate of 9.5 nl min-1 during control periods. Adrenaline elevated SNGFR to a mean value of 22.9 nl min-1 (range 2.4-64.6 nl min-1). Tubular fluid/plasma inulin concentration ratios (TF/Pin) indicated reabsorption of around 74% of the glomerular filtrate by the proximal segments. Comparison of TF/P and urine/plasma inulin concentrations (U/Pin) strongly suggests tubular secretion of water beyond the point of puncture. Adrenaline infusion appears to increase both proximal water reabsorption and distal tubular secretion.
mesh_terms: D000818:Animals; D004284:Dogfish / Q000502:physiology*; D004837:Epinephrine / Q000494:pharmacology*; D005919:Glomerular Filtration Rate / Q000187:drug effects; D007678:Kidney Glomerulus / Q000187:drug effects / Q000502:physiology; D007684:Kidney Tubules / Q000187:drug effects / Q000502:physiology; D009399:Nephrons / Q000187:drug effects / Q000502:physiology*; D012754:Sharks / Q000502:physiology*
chemical_list: D004837:Epinephrine