The lung as a metabolic organ

Area of Science:

• Pulmonary Medicine
• Endocrinology
• Biochemistry

Background:

• The lung is increasingly recognized for its metabolic functions.
• It modulates arterial blood composition through substance removal, release, temporary storage, and activation/inactivation.
• Assessing these functions noninvasively is crucial for understanding lung physiology and pathology.

Purpose of the Study:

• To review existing in vivo noninvasive methods for assessing lung metabolic functions.
• To detail a novel procedure for quantifying pulmonary endothelial amine receptors.
• To explore the application of these methods in human health and disease.

Main Methods:

• Review of published procedures for noninvasive assessment of lung metabolic functions.
• Focus on methods estimating plasma amine clearance by lung endothelial cells.
• Detailed explanation of a new method calculating the number of free pulmonary endothelial amine receptors using radiolabeled amines and extraction fraction.

Main Results:

• Most reviewed procedures rely on measuring lung uptake or extraction fraction of radiolabeled amines.
• The novel procedure, applied in goats using N-isopropyl-p-iodoamphetamine labeled with 123I, quantified the total number of endothelial lung amine receptors as 1.589 X 10(20).

Conclusions:

• Noninvasive methods for assessing lung metabolic functions are valuable tools.
• The discussed methods, particularly the receptor-based approach, can be applied to humans.
• These techniques offer potential for evaluating physiological and pathological conditions of the lung.