|
Rubicon Research Repository >
Rubicon Foundation Archive >
UHMS Meeting Abstracts >
Please use this identifier to cite or link to this item:
http://archive.rubicon-foundation.org/4150
|
| Title: | HYDROSTATIC PRESSURE AND CARDIAC PACEMAKER FUNCTION |
| Authors: | Hogan, PM
Ornhagen, HC
Doubt, TJ |
| Keywords: | animal
canine
Purkinje
bradycardia
pacemaker
pressure
exposure
equipment
hyperbaric conditions |
| Issue Date: | 1977 |
| Abstract: | We have reported previously that elevated hydrostatic pressure slows the beating frequency of mammalian sinus nodes. The present study examined: 1) the affect of pressure on the voltage determinants of automaticity in single pacemaker cells, and 2) the adaptational changes in pacemaker function associated with prolonged exposure to pressure. Spontaneously beating canine Purkinje fibers were subjected to 100 atm of hydrostatic pressure. Intracellular micro-electrode recordings correlated pressure-induced slowing (from 74.5 +/- 4.5 to 60.5 +/- 3.8 beats/min) with a significant reduction in the rate of dyastolic depolarization (from 34.0 +/- 3.1 to 22.5 +/- 3.2 mv/sec). This result suggests that pressure may modify the kinetics of K+ conductance during diastole. Elevated pressure also increased the degree of overdrive suppression of the spontaneous rate, providing further evidence for the negative chronotropic action of pressure. Long-term adaptational responses were demonstrated using the mouse sinus node preparation. After 3 hours of exposure to 150 atm, decompression to 1atm resulted in a beating frequency faster than the initial 1atm control value. The large overshoot indicates that heart rate adapts to high pressure environments. This finding may explain the gradual disappearance of hyperbaric bradycardia noted in human subjects during long periods at elevated pressure. |
| Description: | Abstract of the Undersea and Hyperbaric Medical Society, Inc. Annual Scientific Meeting held May 13-16, 1977. Holiday-Inn, Toronto, Ontario, Canada (http: www.uhms.org) |
| URI: | http://archive.rubicon-foundation.org/4150 |
| Appears in Collections: | UHMS Meeting Abstracts
|
All items in DSpace are protected by copyright, with all rights reserved.
|
