Role of prostaglandins in determining the increased cardiac sympathetic nerve activity in ovine sepsis.
Effective treatment of sepsis remains a significant challenge in intensive care units. During sepsis, there is widespread activation of the sympathetic nervous system, which is thought to have both beneficial and detrimental effects. The sympathoexcitation is thought to be partly due to the developing hypotension, but may also be a response to the inflammatory mediators released. Thus, we investigated whether intracarotid infusion of prostaglandin E2 (PGE2) induced similar cardiovascular changes to those caused by intravenous infusion of Escherichia coli in sheep and whether inhibition of prostaglandin synthesis, with the nonselective cyclooxygenase inhibitor indomethacin, administered at 2 and 8 h after the onset of sepsis, reduced sympathetic nerve activity (SNA), and heart rate (HR). Studies were performed in conscious sheep instrumented to measure mean arterial pressure (MAP), HR, cardiac SNA (CSNA), and renal SNA (RSNA). Intracarotid infusion of PGE2 (50 ng·kg(-1)·min(-1)) increased temperature, CSNA, and HR, but not MAP or RSNA. Sepsis, induced by infusion of E. coli, increased CSNA, but caused an initial, transient inhibition of RSNA. At 2 h of sepsis, indomethacin (1.25 mg/kg bolus) increased MAP and caused reflex decreases in HR and CSNA. After 8 h of sepsis, indomethacin did not alter MAP, but reduced CSNA and HR, without altering baroreflex control. These findings indicate an important role for prostaglandins in mediating the increase in CSNA and HR during the development of hyperdynamic sepsis, whereas prostaglandins do not have a major role in determining the early changes in RSNA.
Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia lindsea.booth@florey.edu.au.
Lindsea C
LC
Booth
Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia.
Rohit
R
Ramchandra
Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia.
Paolo
P
Calzavacca
Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia.
Clive N
CN
May
D000818:Animals; D062186:Arterial Pressure / Q000187:drug effects; D017704:Baroreflex / Q000187:drug effects; D002339:Carotid Arteries; D016861:Cyclooxygenase Inhibitors / Q000008:administration & dosage; D015232:Dinoprostone / Q000008:administration & dosage*; D004195:Disease Models, Animal; D004334:Drug Administration Schedule; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000378:metabolism / Q000382:microbiology / Q000503:physiopathology*; D005260:Female; D006321:Heart / Q000294:innervation*; D006339:Heart Rate / Q000187:drug effects; D007261:Infusions, Intra-Arterial; D007668:Kidney / Q000294:innervation; D018805:Sepsis / Q000188:drug therapy / Q000378:metabolism / Q000382:microbiology / Q000503:physiopathology*; D012756:Sheep; D015398:Signal Transduction / Q000187:drug effects; D013564:Sympathetic Nervous System / Q000187:drug effects* / Q000503:physiopathology; D013997:Time Factors
D016861:Cyclooxygenase Inhibitors; D015232:Dinoprostone
PGE2; baroreflex curve; cardiac sympathetic nerve activity; indomethacin; renal sympathetic nerve activity; sepsis; sheep