5-Hydroxytryptamine-induced microvascular pressure transients in lungs of anaesthetized rabbits

• Published in: Acta physiologica Scandinavica 2001-06, Vol.172 (2), p.81-87
• Main Authors: Sen, N., Glucksberg, M. R., Bhattacharya, S.
• Format: Article
• Language: English
• Subjects: Air breathing; Anesthesia, Inhalation; Animals; Arteries - drug effects; Arteries - physiology; Biological and medical sciences; Blood Pressure - drug effects; Blood Pressure Determination - methods; compensatory vasodilatation; Fundamental and applied biological sciences. Psychology; Lung - blood supply; Lung - drug effects; Lung - physiology; lung micropuncture; Microcirculation - drug effects; pulmonary circulation; Pulmonary Circulation - drug effects; Rabbits; Regional Blood Flow - drug effects; Respiratory system: anatomy, metabolism, gas exchange, ventilatory mechanics, respiratory hemodynamics; segmental pressures; Serotonin - pharmacology; servonull method; Time Factors; Vasoconstriction - drug effects; Veins - drug effects; Veins - physiology; Vertebrates: respiratory system
• ISSN: 0001-6772; 1365-201X
• DOI: 10.1046/j.1365-201X.2001.00846.x

We determined lung microvascular pressure transients induced by 5‐hydroxytryptamine (5HT), by the micropuncture technique. We mechanically ventilated anaesthetized (halothane 0.8%), open‐chested rabbits, in which we recorded pulmonary artery (PA), left atrial (LA) and carotid artery pressures and cardiac output. For 4‐min periods of stopped ventilation, we constantly inflated the lung with airway pressure of 7 cmH2O, then micropunctured the lung to determine pressures in arterioles and venules of 20–25 μm diameter. An intravenous bolus infusion of 5HT (100 μg), increased total pulmonary vascular resistance by 59%. Prior to 5HT infusion, the arterial, microvascular and venous segments comprised 30, 50 and 19% of the total pulmonary vascular pressure drop, respectively. However 14 s after 5HT infusion, the PA‐arteriole pressure difference (arterial pressure drop) increased 46%, while the venule‐LA pressure difference (venous pressure drop) increased >100%. The arteriole–venule pressure difference (microvascular pressure drop) was abolished. The increase in the arterial pressure drop was maintained for 4.8 min, whereas the increased venous pressure drop reverted to baseline in