Influence of nitroglycerin on splanchnic capacity and splanchnic capacity-cardiac output relationship.
It has been postulated, but not tested directly, that nitroglycerin's venodilatory effects attenuate cardiac output. Thus, the present study examined the importance of changes in splanchnic capacity, as assessed by scintigraphy, in the regulation of cardiac output during nitroglycerin administration in 16 anesthetized pigs under conditions of carotid sinus denervation and cervical vagotomy. With nitroglycerin administration (0.5 mg/min i.v.) for 5 min, systemic arterial pressure decreased from 115 +/- 7 to 95 +/- 7 mmHg (P < 0.0001), portal vein pressure decreased from 9.0 +/- 0.5 to 8.5 +/- 0.5 mmHg (P < 0.0001), portal flow increased from 637 +/- 49 to 668 +/- 60 ml/min (P = 0.09), and transhepatic resistance decreased from 7.5 +/- 1.5 to 6.5 +/- 1.0 mmHg.min.l-1 (P < 0.01), but cardiac output was unchanged (1,929 +/- 126 to 1,890 +/- 138 ml/min). Total splanchnic intravascular volume (VI) increased 1.6 +/- 1.0% (P < 0.05, 14 +/- 10 ml). This increase was due to an increment in extrahepatosplenic (mesenteric) VI (12.9 +/- 1.9%, P < 0.0001), since splenic VI decreased (9.6 +/- 2.8%, P < 0.0001) and hepatic VI did not change. After splenectomy, nitroglycerin infusions at doses of 0.5 and 2 mg/min were associated with increases in total splanchnic VI of 3.7 +/- 1.2% (P < 0.0001, 30 +/- 10 ml) and 7.6 +/- 1.7% (P < 0.001, 59 +/- 10 ml) due entirely to increases in mesenteric volume of 9.9 +/- 2.7% (P < 0.0001) and 16.5 +/- 1.9% (P < 0.0001), respectively, but cardiac output was unchanged at the end of infusion at either dose.(ABSTRACT TRUNCATED AT 250 WORDS)
Morse
M A
MA
Department of Medicine, Yale University School of Medicine, New Haven, Connecticut 06510.
Rutlen
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DL
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects*; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D005996:Nitroglycerin / Q000494:pharmacology*; D011652:Pulmonary Circulation / Q000187:drug effects; D011877:Radionuclide Imaging; D012039:Regional Blood Flow / Q000187:drug effects; D013670:Sodium Pertechnetate Tc 99m; D013152:Splanchnic Circulation / Q000187:drug effects*; D013156:Splenectomy; D013552:Swine; D014655:Vascular Resistance / Q000187:drug effects
D013670:Sodium Pertechnetate Tc 99m; D005996:Nitroglycerin