Role of renocortical cyclooxygenase-2 for renal vascular resistance and macula densa control of renin secretion.
This study aimed to assess the role of cyclooxygenase-2 (COX-2)-derived prostanoids for the macula densa control of renal afferent arteriolar resistance and for renin secretion. For this purpose, studied were the effects of blocking macula densa salt transport by the loop diuretic bumetanide (100 microM) on renal perfusate flow and on renin secretion in isolated perfused rats, in which renocortical COX-2 expression was prestimulated in vivo by treatment with the angiotensin-converting enzyme inhibitor ramipril, with low-salt diet, or with a combination of both. These maneuvers stimulated COX-2 expression in an order of ramipril + low salt>> low salt > ramipril > controls. Flow rates through isolated kidneys at a constant pressure of 100 mmHg were dependent on the pretreatment regimen, in the way that they went in parallel with COX-2 expression. The COX-2 inhibitor NS-398 (10 microM) lowered flow rates depending on the COX-2 expression level and was most pronounced therefore after pretreatment with low salt + ramipril. NS-398 did not change the increase of flow in response to bumetanide but attenuated the stimulation of renin secretion in response to bumetanide in a manner depending on the expression level of COX-2. These findings suggest that in states of increased renocortical expression of COX-2, overall renal vascular resistance and the macula densa control of renin secretion become dependent on COX-2-derived prostanoids.
Castrop
Hayo
H
Institut für Physiologie der Universität Regensburg, Regensburg, Germany.
Schweda
Frank
F
Institut für Physiologie der Universität Regensburg, Regensburg, Germany.
Schumacher
Karl
K
Institut für Anatomie der Universität Regensburg, Regensburg, Germany.
Wolf
Konrad
K
Institut für Physiologie der Universität Regensburg, Regensburg, Germany.
Kurtz
Armin
A
Institut für Physiologie der Universität Regensburg, Regensburg, Germany.
D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D002034:Bumetanide / Q000494:pharmacology; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004039:Diet, Sodium-Restricted; D004232:Diuretics / Q000494:pharmacology; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D007672:Kidney Cortex / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D008297:Male; D009578:Nitrobenzenes / Q000494:pharmacology; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017257:Ramipril / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012079:Renal Circulation / Q000502:physiology*; D012083:Renin / Q000378:metabolism*; D013449:Sulfonamides / Q000494:pharmacology; D014655:Vascular Resistance / Q000502:physiology
D000806:Angiotensin-Converting Enzyme Inhibitors; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D004232:Diuretics; D007527:Isoenzymes; D009578:Nitrobenzenes; D012333:RNA, Messenger; D013449:Sulfonamides; D002034:Bumetanide; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D012083:Renin; D017257:Ramipril