Forearm vascular and neuroendocrine responses to graded water immers

Authors: Gabrielsen A (1) , Videbaek R (2) , Johansen LB (1) , Warberg J (3) , Christensen NJ (4) , Pump B (1) , Norsk P (1)
(1) Danish Aerospace Medical Centre of Research, National University Hospital, Rigshospitalet (2) The Heart Center, National University Hospital, Rigshospitalet (3) Institute of Medical Physiology, The Panum Institute, University of Copenhagen (4) Department of Internal Medicine and Endocrinology, Herlev Hospital, University of Copenhagen
Source: Acta Physiol Scand. 2000 Jun;169(2):87-94
DOI: 10.1046/j.1365-201x.2000.00680.x Publication date: 2000 Jun E-Publication date: Dec. 24, 2001 Availability: abstract Copyright: © 2001, John Wiley and Sons
Language: English Countries: Not specified Location: Not specified Correspondence address: Anders Gabrielsen MD DAMEC Research, Rigshospitalet 7805, 20 Tagensvej, DK-2200 Copenhagen, Denmark.


Article abstract

The hypothesis that graded expansion of central blood volume by water immersion to the xiphoid process and neck would elicit a graded decrease in forearm vascular resistance was tested. Central venous pressure increased (P < 0.05) by 4.2 +/- 0.4 mmHg (mean +/- SEM) during xiphoid immersion and by 10.4 +/- 0.5 mmHg during neck immersion. Plasma noradrenaline was gradually suppressed (P < 0.05) by 62 +/- 8 and 104 +/- 11 pg mL-1 during xiphoid and neck immersion, respectively, indicating a graded suppression of sympathetic nervous activity. Plasma concentrations of arginine vasopressin were suppressed by 1.5 +/- 0.5 pg mL-1 (P < 0.05) during xiphoid immersion and by 2.0 +/- 0.5 pg mL-1 during neck immersion (P < 0.05 vs. xiphoid immersion). Forearm subcutaneous vascular resistance decreased to the same extent by 26 +/- 9 and 28 +/- 4% (P < 0.05), respectively, during both immersion procedures, whereas forearm skeletal muscle vascular resistance declined only during neck immersion by 27 +/- 6% (P < 0.05). In conclusion, graded central blood volume expansion initiated a graded decrease in sympathetic nervous activity and AVP-release. Changes in forearm subcutaneous vascular resistance, however, were not related to the gradual withdrawal of the sympathetic and neuroendocrine vasoconstrictor activity. Forearm skeletal muscle vasodilatation exhibited a more graded response with a detectable decrease only during immersion to the neck. Therefore, the forearm subcutaneous vasodilator response reaches saturation at a lower degree of central volume expansion than that of forearm skeletal muscle.

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