title: Coronary responses to cold air inhalation following afferent and efferent blockade.
abstract: Cardiac ischemia and angina pectoris are commonly experienced during exertion in a cold environment. In the current study we tested the hypotheses that oropharyngeal afferent blockade (i.e., local anesthesia of the upper airway with lidocaine) as well as systemic β-adrenergic receptor blockade (i.e., intravenous propranolol) would improve the balance between myocardial oxygen supply and demand in response to the combined stimulus of cold air inhalation (-15 to -30°C) and isometric handgrip exercise (Cold + Grip). Young healthy subjects underwent Cold + Grip following lidocaine, propranolol, and control (no drug). Heart rate, blood pressure, and coronary blood flow velocity (CBV, from Doppler echocardiography) were continuously measured. Rate-pressure product (RPP) was calculated, and changes from baseline were compared between treatments. The change in RPP at the end of Cold + Grip was not different between lidocaine (2,441 ± 376) and control conditions (3,159 ± 626); CBV responses were also not different between treatments. With propranolol, heart rate (8 ± 1 vs. 14 ± 3 beats/min) and RPP responses to Cold + Grip were significantly attenuated. However, at peak exercise propranolol also resulted in a smaller ΔCBV (1.4 ± 0.8 vs. 5.3 ± 1.4 cm/s, P = 0.035), such that the relationship between coronary flow and cardiac metabolism was impaired under propranolol (0.43 ± 0.37 vs. 2.1 ± 0.63 arbitrary units). These data suggest that cold air breathing and isometric exercise significantly influence efferent control of coronary blood flow. Additionally, β-adrenergic vasodilation may play a significant role in coronary regulation during exercise.
authors.affiliation: Pennsylvania State University College of Medicine, Penn State Hershey Heart and Vascular Institute, Hershey, Pennsylvania mmuller1@hmc.psu.edu.
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Muller
authors.affiliation: Pennsylvania State University College of Medicine, Penn State Hershey Heart and Vascular Institute, Hershey, Pennsylvania.
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Gao
authors.affiliation: Pennsylvania State University College of Medicine, Penn State Hershey Heart and Vascular Institute, Hershey, Pennsylvania.
authors.forename: Patrick M
authors.initials: PM
authors.lastname: McQuillan
authors.affiliation: Pennsylvania State University College of Medicine, Penn State Hershey Heart and Vascular Institute, Hershey, Pennsylvania.
authors.forename: Urs A
authors.initials: UA
authors.lastname: Leuenberger
authors.affiliation: Pennsylvania State University College of Medicine, Penn State Hershey Heart and Vascular Institute, Hershey, Pennsylvania.
authors.forename: Lawrence I
authors.initials: LI
authors.lastname: Sinoway
mesh_terms: D000280:Administration, Inhalation; D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage; D000328:Adult; D000779:Anesthetics, Local / Q000008:administration & dosage; D001783:Blood Flow Velocity; D001794:Blood Pressure; D003080:Cold Temperature; D003326:Coronary Circulation / Q000187:drug effects; D003331:Coronary Vessels / Q000187:drug effects / Q000502:physiology*; D005260:Female; D018737:Hand Strength; D006339:Heart Rate; D006801:Humans; D007262:Infusions, Intravenous; D001239:Inhalation; D007537:Isometric Contraction; D008012:Lidocaine / Q000008:administration & dosage; D008297:Male; D009206:Myocardium / Q000378:metabolism; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology*; D009476:Neurons, Efferent / Q000187:drug effects / Q000502:physiology*; D010101:Oxygen Consumption; D011433:Propranolol / Q000008:administration & dosage; D013997:Time Factors; D014664:Vasodilation
chemical_list: D000319:Adrenergic beta-Antagonists; D000779:Anesthetics, Local; D008012:Lidocaine; D011433:Propranolol
keywords: blood pressure; heart rate; lidocaine; oropharynx; propranolol; vascular resistance