3. Lastly, very recent work has completely changed our understanding of the control of normal, basal mucus and solute secretion in the human airways and gut. Here-to-fore it was believed that cholinergic mechanisms controlled airway mucus secretion. This recent and still emerging work shows that in fact it is VIP and Substance P which act individually and synergistically in the control of both normal basal human airway mucus production and in regulating gut secretion. This very new work gives a unifying hypothesis to the seemingly disparate entities of PLE and PB: since Substance P and VIP control normal basal human airway secretion and stimulated human gut protein secretion, increases in pulmonary venous and/or gut arterial levels of these peptides can be the basis for PLE and PB. The GI, cardiac and pulmonary physiology and pharmacologic treatment of patients with fenestrated Fontans is a perfect setting for this interaction to occur.