AJP - Lung Cellular and Molecular Physiology, Vol 273, Issue 1 264-L274, Copyright © 1997 by American Physiological Society

ARTICLES

Pulmonary clearance and release of norepinephrine and epinephrine in newborn lambs

J. J. Smolich, H. S. Cox, G. Eisenhofer and M. D. Esler
Institute of Reproduction and Development, Monash University, Clayton, Victoria, Australia.

To examine the pulmonary kinetics of the catecholamines norepinephrine and epinephrine immediately after birth, eight fetal lambs were instrumented with vascular catheters under general anesthesia at 133-134 days gestation (term = 147 days) and were delivered by cesarean section 1 wk later. Pulmonary norepinephrine and epinephrine kinetics were then studied 1 and 4 h after birth using radiotracer dilution methodology. The pulmonary fractional extraction of norepinephrine was similar in 1-h (0.111 +/- 0.021) and 4-h (0.117 +/- 0.023) lambs and constituted 24 +/- 5 and 32 +/- 9% of total body norepinephrine clearance, respectively. Pulmonary removal of epinephrine was less pronounced with a fractional extraction of 0.035 +/- 0.017 in 1-h and 0.036 +/- 0.013 in 4-h lambs, which corresponded to 8 +/- 4 and 9 +/- 3% of total body epinephrine clearance, respectively. Pulmonary spillover of norepinephrine into the circulation was similar in 1-h (79 +/- 26 ng.min-1.kg-1) and 4-h (82 +/- 18 ng.min-1.kg-1) lambs, and this comprised 27 +/- 8 and 42 +/- 8% of total body norepinephrine spillover, respectively. Pulmonary epinephrine spillover was not detectable at 1 h, but it occurred in all 4-h lambs, averaging 4.7 +/- 0.8 ng.min-1.kg-1 or 20 +/- 6% of epinephrine total body spillover. These findings indicate that the lungs of newborn lambs 1) are a major site for removal of norepinephrine and epinephrine from the circulation; 2) release a substantial quantity of norepinephrine into the circulation, consistent with the presence of tonic pulmonary sympathetic nerve activity; and 3) constitute a significant extra-adrenal source of plasma epinephrine.

This article has been cited by other articles:

				V. Houfflin-Debarge, A. Delelis, S. Jaillard, B. Larrue, P. Deruelle, A. S. Ducloy, F. Puech, and L. Storme Effects of nociceptive stimuli on the pulmonary circulation in the ovine fetus Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2005; 288(2): R547 - R553. [Abstract] [Full Text] [PDF]

				E. M. Mbaku, L. Zhang, W. J. Pearce, S. P. Duckles, and J. Buchholz Chronic hypoxia alters the function of NOS nerves in cerebral arteries of near-term fetal and adult sheep J Appl Physiol, February 1, 2003; 94(2): 724 - 732. [Abstract] [Full Text] [PDF]

				S. Jaillard, V. Houfflin-Debarge, Y. Riou, T. Rakza, S. Klosowski, P. Lequien, and L. Storme Effects of catecholamines on the pulmonary circulation in the ovine fetus Am J Physiol Regulatory Integrative Comp Physiol, August 1, 2001; 281(2): R607 - R614. [Abstract] [Full Text] [PDF]

				J. Buchholz, K. Edwards-Teunissen, and S. P. Duckles Impact of development and chronic hypoxia on NE release from adrenergic nerves in sheep arteries Am J Physiol Regulatory Integrative Comp Physiol, March 1, 1999; 276(3): R799 - R808. [Abstract] [Full Text] [PDF]

				J. J. Smolich, H. S. Cox, and M. D. Esler Contribution of lungs to desipramine-induced changes in whole body catecholamine kinetics in newborn lambs Am J Physiol Regulatory Integrative Comp Physiol, January 1, 1999; 276(1): R243 - R250. [Abstract] [Full Text] [PDF]