Tubular signal for the renin activity in the juxtaglomerular apparatus.
To investigate the effect of ionic composition of the tubular fluid in the macula densa segment upon the JGA renin activity, the macula densa segment was perfused with different solutions and the renin activity in the attached juxtaglomerular apparatus was measured. Increasing the sodium chloride concentration at the macula densa by perfusion with Ringer's solution or saline increased the JGA renin activity. An activation of JGA renin activity did not occur when amiloride was added to the saline or when the animals were pretreated by a high-salt diet. Perfusing the macula densa segment with a sodium-chloride-free solution, with sodium- or chloride-substituted solutions, or with mock early distal fluid, did not affect the JGA renin activity. These data are in accord with the proposition that in the tubuloglomerular feedback mechanism the renin-angiotensin salt diet. Perfusing the macula densa segment with a sodium-chloride-free solution, with sodium- or chloride-substituted solutions, or with mock early distal fluid, did not affect the JGA renin activity. These data are in accord with the proposition that in the tubuloglomerular feedback mechanism the renin-angiotensin salt diet. Perfusing the macula densa segment with a sodium-chloride-free solution, with sodium- or chloride-substituted solutions, or with mock early distal fluid, did not affect the JGA renin activity. These data are in accord with the proposition that in the tubuloglomerular feedback mechanism the renin-angiotensin system in the juxtaglomerular apparatus acts as a local, humoral mediator between the signal perceived at the macula densa and the hemodynamic response at the glomerulus. The mediation by the renin-angiotensin system, which is influenced by the sodium chloride balance, allows the sensitivity of this control of GFR to be adjusted in a homeostatically appropriate manner.
D000818:Animals; D005246:Feedback; D007606:Juxtaglomerular Apparatus / Q000201:enzymology*; D007684:Kidney Tubules / Q000502:physiology*; D007686:Kidney Tubules, Distal / Q000502:physiology*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012083:Renin / Q000032:analysis*; D012965:Sodium Chloride / Q000494:pharmacology
D012965:Sodium Chloride; D012083:Renin