Muscle metaboreflex activation (MMA) during dynamic exercise increases cardiac work and myocardial O2 demand via increases in heart rate, ventricular contractility, and afterload. This increase in cardiac work should lead to metabolic coronary vasodilation; however, no change in coronary vascular conductance occurs. This indicates that the MMA-induced increase in sympathetic activity to the heart, which raises heart rate, ventricular contractility, and cardiac output, also elicits coronary vasoconstriction.
View Article and Find Full Text PDFMuscle metaboreflex activation during dynamic exercise induces a substantial increase in cardiac work and oxygen demand via a significant increase in heart rate, ventricular contractility, and afterload. This increase in cardiac work should cause coronary metabolic vasodilation. However, little if any coronary vasodilation is observed due to concomitant sympathetically induced coronary vasoconstriction.
View Article and Find Full Text PDFBackground And Objective: Pulmonary delivery of aerosols during high-frequency oscillatory ventilation (HFOV) has not been studied in vivo. This study investigated the pulmonary delivery of aerosolized gadopentetate dimeglumine (Gd-DTPA) in a HFOV circuit in piglets using MRI to visualize contrast excretion in the kidneys.
Methods: Four ventilated piglets (3-7 days old, 1.
Ischemia of active skeletal muscle elicits a pressor response termed the muscle metaboreflex. We tested the hypothesis that in normal dogs during dynamic exercise, graded muscle metaboreflex activation (MMA) would progressively attenuate spontaneous heart rate baroreflex sensitivity (SBRS). The animals were chronically instrumented to measure heart rate (HR), cardiac output (CO), mean and systolic arterial pressure (MAP and SAP), and left ventricular systolic pressures (LVSP) at rest and during mild or moderate treadmill exercise before and during progressive MMA [via graded reductions of hindlimb blood flow (HLBF)].
View Article and Find Full Text PDFPulm Pharmacol Ther
October 2008
Objective: To study the toxicity of inhaled PGE1 (IPGE1) in healthy ventilated piglets.
Methods: Mechanically ventilated anesthetized piglets received either high dose IPGE1 (IPGE1 group) or nebulized saline (control group) continuously for 24h. Cardio-respiratory parameters, complete blood counts and serum electrolytes were monitored.
Study Objective: By using an animal model, we determine whether repeated exposures to a conducted electrical weapon could have physiologic consequences.
Methods: Exposures to the Stinger S-400 conducted electrical weapon were applied to 10 healthy, anesthetized, Yorkshire-cross, male swine by attaching probes from the cartridge to the sternal notch and anterolateral thorax at a distance of 21.5 cm.