Abstract
Intravenous lipid infusion in newborn lambs causes acute pulmonary hypertension followed by a sustained increase in lung lymph flow and reduction in lymph protein concentration (Teague et al, Pediatr Res 18:313A, 1984). We found that plasma concentrations of the pulmonary vasoconstrictors thromboxane B2 and serotonin (5-HT) both increased during lipid infusion in lambs. To see if these vasoactive substances might play a role in the lung microvascular changes associated with lipid infusion, we pretreated 14 lambs with suitable inhibitors: 8 received indomethacin (1-5 mg/kg/h for 6h) and 6 received a 5-HT blocker, methysergide (0.6 mg/kg/d for 2d) before and during lipid infusion. We measured pulmonary artery (Ppa) and left atrial pressures, lung lymph flow (QL), and lymph and plasma protein concentrations during a 2-4h control period followed by 6h of constant lipid infusion, 0.25 g/kg/h. Indomethacin alone increased Ppa and QL, but lipid infusion in the presence of indomethacin caused no further increases of either Ppa or QL. Methysergide reduced steady-state QL without preventing the acute pulmonary hypertension associated with lipid infusion. In 6 lambs, intravenous infusion of 5-HT (4-6 μg/kg/min for 5h) increased QL without affecting Ppa. These results suggest that cyclooxygenase products of arachidonic acid metabolism may cause the acute pulmonary hypertension that occurs during lipid infusion, whereas 5-HT may be responsible for the steady-state increase in lung fluid filtration.
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Teague, W., Raj, J., Braun, D. et al. 1540 MECHANISM OF INCREASED LUNG FLUID FILTRATION DURING LIPID INFUSION IN LAMBS. Pediatr Res 19, 367 (1985). https://doi.org/10.1203/00006450-198504000-01564
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DOI: https://doi.org/10.1203/00006450-198504000-01564