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Decreased capillary filtration but maintained venous compliance in the lower limb of aging women
Linköpings universitet, Institutionen för medicin och hälsa, Fysiologi. Linköpings universitet, Hälsouniversitetet.
Linköpings universitet, Institutionen för medicin och hälsa, Fysiologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Hjärtcentrum, Thorax-kärlkliniken.ORCID-id: 0000-0002-9095-403X
2007 (engelsk)Inngår i: American Journal of Physiology. Heart and Circulatory Physiology, ISSN 0363-6135, E-ISSN 1522-1539, Vol. 293, s. H3568-H3574Artikkel i tidsskrift (Fagfellevurdert) Published
Abstract [en]

There are sex-related differences in venous compliance and capillary filtration in the lower limbs, which to some extent can explain the susceptibility to orthostatic intolerance in young women. With age, venous compliance and capacitance are reduced in men. This study was designed to evaluate age-related changes in venous compliance and capillary filtration in the lower limbs of healthy women. Included in this study were 22 young and 12 elderly women (23.1 ± 0.4 and 66.4 ± 1.4 yr). Lower body negative pressure (LBNP) of 11, 22, and 44 mmHg created defined transmural pressure gradients in the lower limbs. A plethysmographic technique was used on the calf to assess venous capacitance and net capillary filtration. Venous compliance was calculated with the aid of a quadratic regression equation. No age-related differences in venous compliance and capacitance were found. Net capillary filtration and capillary filtration coefficient (CFC) were lower in elderly women at a LBNP of 11 and 22 mmHg (0.0032 vs. 0.0044 and 0.0030 vs. 0.0041 ml·100 ml–1·min–1·mmHg–1, P < 0.001). At higher transmural pressure (LBNP, 44 mmHg), CFC increased by 1/3 (0.010 ml·100 ml–1·min–1·mmHg–1) in the elderly (P < 0.001) but remained unchanged in the young women. In conclusion, no age-related decrease in venous compliance and capacitance was seen in women. However, a decreased CFC was found with age, implying reduced capillary function. Increasing transmural pressure increased CFC in the elderly women, indicating an increased capillary susceptibility to transmural pressure load in dependent regions. These findings differ from earlier studies on age-related effects in men, indicating sex-specific vascular aging both in the venous section and microcirculation.

sted, utgiver, år, opplag, sider
2007. Vol. 293, s. H3568-H3574
Emneord [en]
Capillary filtration coefficient; lower body negative pressure; age
HSV kategori
Identifikatorer
URN: urn:nbn:se:liu:diva-15417DOI: 10.1152/ajpheart.00725.2007OAI: oai:DiVA.org:liu-15417DiVA, id: diva2:114144
Tilgjengelig fra: 2008-11-06 Laget: 2008-11-06 Sist oppdatert: 2017-12-14bibliografisk kontrollert
Inngår i avhandling
1. Cardiovascular responses to hypovolemic circulatory stress in women: With special reference to venous compliance and capacitance
Åpne denne publikasjonen i ny fane eller vindu >>Cardiovascular responses to hypovolemic circulatory stress in women: With special reference to venous compliance and capacitance
2008 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Acute haemorrhage is a leading cause of death in trauma. Young women (YW) seem more susceptible to hypovolemic circulatory stress than young men (YM), but the underlying mechanisms are not clear. Elderly subjects are more vulnerable to haemorrhage, with a decreased defence of central blood volume in elderly men, but the defence has not been evaluated in elderly women  (EW). The aims were to assess differences in cardiovascular responses to hypovolemic circulatory stress, emphasizing compensatory mechanisms to maintain central blood volume in YW, EW and in women prone to vaso‐vagal reaction (VW).

Lower body negative pressure (LBNP) was used as a model for haemorrhage and to create acute hypovolemic stress. Volumetric techniques were used to assess venous compliance, capacitance and capillary fluid exchange both caused by LBNP in the calf and the response to maintain central blood volume.

LBNP induced a comparable hypovolemic stimulus in YW and YM, with lower calf venous compliance and capacitance but higher net capillary fluid filtration in YW. YW responded with smaller vasoconstriction without association between P‐NE and peripheral vascular resistance in contrast to YM. Venous capacitance response was decreased with time in YW. Further, net capillary fluid absorption from peripheral tissues to central circulation was decreased in YW in response to hypovolemic stress. All in all, this indicates less efficiency to defend central blood volume in young women.

Calf venous compliance and capacitance was maintained in EW compared to YW but capillary filtration was decreased, implying reduced capillary function with age. With increasing transmural pressures however, filtration and capillary filtration coefficient (CFC) increased indicating increased capillary susceptibility to transmural pressure load in dependent regions with age. Heart rate increase was attenuated in EW while peripheral vascular conductance was maintained suggesting reduced cardiovagal baroreceptor function in response to hypovolemia with age. Venous capacitance response and fluid absorption from peripheral tissues to central circulation were decreased with age, indicating less efficiency to defend central blood volume.

LBNP induced a slower hypovolemic stimulus in VW compared with nonvagal women. Further, the cardiopulmonary baroreflex was less efficient, and the venous capacitance response from peripheral tissues to central circulation was decreased, which may explain their susceptibility to orthostatic challenge.

sted, utgiver, år, opplag, sider
Linköping: Linköping University Electronic Press, 2008. s. 70
Serie
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1087
HSV kategori
Identifikatorer
urn:nbn:se:liu:diva-15420 (URN)978-91-7393-756-6 (ISBN)
Disputas
2008-11-21, Elsa Brändström salen, Hälsouniversitetet, Campus US, Linköpings universitet, Linköping, 09:15 (engelsk)
Opponent
Veileder
Tilgjengelig fra: 2008-11-06 Laget: 2008-11-06 Sist oppdatert: 2020-03-29bibliografisk kontrollert

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