5-Hydroxytryptamine-induced microvascular pressure transients in lungs of anaesthetized rabbits.
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 microm diameter. An intravenous bolus infusion of 5HT (100 microg), 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 <1 min. We conclude that in the rabbit lung in situ, a 5HT bolus causes sustained arterial constriction and a strong but transient venous constriction.
Sen
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Department of Physiology and Cellular Biophysics, College of Physicians and Surgeons, Columbia University, St Luke's-Roosevelt Hospital Center, New York, NY 10019, USA.
Glucksberg
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MR
Bhattacharya
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S
D000769:Anesthesia, Inhalation; D000818:Animals; D001158:Arteries / Q000187:drug effects / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects*; D001795:Blood Pressure Determination / Q000379:methods; D008168:Lung / Q000098:blood supply / Q000187:drug effects* / Q000502:physiology; D008833:Microcirculation / Q000187:drug effects*; D011652:Pulmonary Circulation / Q000187:drug effects*; D011817:Rabbits; D012039:Regional Blood Flow / Q000187:drug effects; D012701:Serotonin / Q000494:pharmacology*; D013997:Time Factors; D014661:Vasoconstriction / Q000187:drug effects; D014680:Veins / Q000187:drug effects / Q000502:physiology
D012701:Serotonin