Abstract
Summary: We compared the concentration-response relationship of intralobar pulmonary arteries to l-norepinephrine with that of femoral arteries from newborn lambs. In addition, the effect of inhibition of the neuronal and extra-neuronal uptake mechanisms on these concentration-response relationships was examined.
Concentration-response curves on 10 intralobar pulmonary arteries were performed with and without inhibition of the uptake mechanisms. Uptake inhibition shifts the curve to the left; thus, the-log EC50 with uptake inhibition (6.63 ± 0.15) is greater than that without uptake inhibition (6.13 ± 0.14). Similar curves on 10 femoral arteries demonstrated that the-log EC50 with and without uptake inhibition (6.20 ± 0.13 and 6.00 ± 0.04, respectively) are not statistically different.
Because, in the presence of intact uptake mechanisms the concentration of l-norepinephrine in the a-receptor microenvironment is less than that placed in the organ bath, the appropriate comparison of pulmonary and femoral arterial response to l-norepinephrine stimulation requires uptake inhibition in both vessels. The concentration-response curve with uptake inhibition for the intralobar pulmonary artery is significantly to the left of that for the femoral; the-log EC50 for the pulmonary vessel (6.63 ± 0.15) is greater than that of the femoral vessel (6.20 ± 0.13). The intralobar pulmonary artery in vitro is more sensitive to l-norepinephrine stimulation than is the femoral.
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Green, R., Leffler, C. A Comparison of the Sensitivities of Neonatal Ovine Pulmonary and Femoral Arteries to l-Norepinephrine Stimulation. Pediatr Res 18, 244–247 (1984). https://doi.org/10.1203/00006450-198403000-00005
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DOI: https://doi.org/10.1203/00006450-198403000-00005