Accession Number:

ADA618698

Title:

Autonomic Mechanisms Associated with Heart Rate and Vasoconstrictor Reserves

Descriptive Note:

Journal article

Corporate Author:

ARMY INST OF SURGICAL RESEARCH FORT SAM HOUSTON TX

Report Date:

2011-11-15

Pagination or Media Count:

10.0

Abstract:

Introduction Hemorrhage is accompanied by baroreflex-mediated tachycardia and vasoconstriction. The difference between baseline and maximum responses is defined as the heart rate HR and vasoconstrictor reserve . Objective To test the hypothesis that higher HR and vasoconstrictor reserves in subjects with high tolerance HT to central hypovolemia is associated with greater reserve for sympathoexcitation and vagal withdrawal compared with low tolerant LT subjects. Methods R R intervals RRI, systolic arterial pressure SAP, estimated stroke volume, and muscle sympathetic nerve activity MSNA were measured during lower body negative pressure LBNP designed to induce pre-syncope. Subjects with tolerance 60 mmHg LBNP were classified as LT n 22 while subjects who tolerated LBNP levels 60 mmHg were classified as HT n 56. Spontaneous cardiac baroreflex sensitivity BRS was assessed via RRISAP down down sequences.

Subject Categories:

  • Anatomy and Physiology
  • Medicine and Medical Research

Distribution Statement:

APPROVED FOR PUBLIC RELEASE