The influence of tumour necrosis factor-alpha on the cardiovascular system of anaesthetized rats.
The effects of two vasoactive agents (adenosine A2A agonist, CGS 21680, and adrenoceptor agonist, noradrenaline) were examined on cardiac output (CO), heart rate (HR), blood pressure (BP), mean circulatory filling pressure (Pmcf), resistance to venous return, arterial resistance, dP/dt, plasma levels of NO2-/NO3-, and inducible nitric oxide synthase (iNOS) activity in lungs ex vivo, following treatment with tumour necrosis factor-alpha (TNF-alpha; 30 microg/kg) in anaesthetized rats. Treatment with TNF-alpha produced significant reduction in CO (41+/-2%), dP/dt (26+/-3%), BP (26+/-2%) and Pmcf (27+/-4%; n=6; mean+/-SEM), but increased arterial resistance. There were no significant changes in the plasma levels of NO2-/NO3-levels over time following treatment with TNF-alpha, but there was a significant increase (approximately twofold) in the activity of the iNOS in the lungs of animals treated with TNF-alpha. Administration of CGS 21680 (1.0 microg/kg per min) significantly increased CO (44+/-6%), HR (12+/-2%), Pmcf (24+/-4%) and dP/dt (24+/-5%) in TNF-alpha-treated rats. CGS 21680 also significantly reduced arterial resistance (33+/-2%) without altering resistance to venous return in TNF-alpha-treated rats. While noradrenaline (1.0 microg/kg per min) infusion did not significantly increase CO, it did significantly increase HR (12+/-1%), BP (55+/-9%), Pmcf (47+/-5%), dP/dt (65+/-7%), resistance to venous return (64+/-20%), and arterial resistance (41+/-16%) in TNF-alpha-treated animals. The reduction in BP due to administration of TNF-alpha is the result of significant reduction in CO. Consequently, the decline in CO can be attributed to a combination of a negative inotropic effect as well as a reduction in Pmcf. It is evident that infusion with CGS 21680 could reverse the negative impact of TNF-alpha on CO by increasing dP/dt, Pmcf and HR as well as a reduction in arterial resistance. The fact that noradrenaline did not significantly increase CO in TNF-alpha-treated rats can be attributed to increased arterial resistance as well increase in resistance to venous return.
Tabrizchi
R
R
Division of Basic Medical Sciences, Faculty of Medicine, Memorial University of Newfoundland, Health Sciences Centre, St John's, Canada. rtabrizc@morgan.ucs.mun.ca
D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D002319:Cardiovascular System / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D008168:Lung / Q000201:enzymology; D008297:Male; D009566:Nitrates / Q000097:blood; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D009573:Nitrites / Q000097:blood; D009638:Norepinephrine / Q000494:pharmacology; D010627:Phenethylamines / Q000494:pharmacology; D058906:Purinergic P1 Receptor Agonists; D051381:Rats; D020318:Rats, Long-Evans; D013318:Stroke Volume / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D014655:Vascular Resistance / Q000187:drug effects
D000316:Adrenergic alpha-Agonists; D009566:Nitrates; D009573:Nitrites; D010627:Phenethylamines; D058906:Purinergic P1 Receptor Agonists; D014409:Tumor Necrosis Factor-alpha; C061282:2-(4-(2-carboxyethyl)phenethylamino)-5'-N-ethylcarboxamidoadenosine; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D000241:Adenosine; D009638:Norepinephrine