Effects of oestrogen on haemodynamic and vascular reactivity - A study in animal models and humans
Year: 2007
Type: dissertation
Abstract: Effects of Oestrogen on Haemodynamic and Vascular Reactivity\nA study in animal models and humans\nLisa Brandin\nInstitute of Medicine, Department of Emergency and Cardiovascular Medicine,\nSahlgrenska University Hospital/Östra, Sahlgrenska Academy,\nGöteborg University, Göteborg, Sweden\nABSTRACT\nPrevious studies have shown that oestrogen, the female sex hormone, plays a protective role\nin the cardiovascular system. However the site of action remains incompletely understood.\nLarge clinical interventional trials have not proven that longer treatment with oestrogen plus\nprogesterone yields lower incidence of cardiovascular outcomes, suggesting that hormone\nreplacement therapy (HRT) might protect only a selective group of postmenopausal women.\nThe present study treated normo- and hypertensive female rats and postmenopausal women\nwith oestrogen for short and longer time periods. We also investigated the acute effect of\n17b-estradiol on isolated small resistance arteries and the effects of oestrogen treatment on\nvascular reactivity and endothelial function in a wire-myograph. Further, we recorded haemodynamic\nparameters during daily life and stress, and evaluated the effect of HRT on the\nautonomic nervous systems of hypertensive women by evaluating heart rate variability (HRV)\nwith 24 h analysis.\nBlood pressure (BP) was attenuated after 24 hour treatment with 17b-estradiol in normotensive\npostmenopausal women and normo- and hypertensive rats. In hypertensive rats a lowered\nBP sustained after 10 days of treatment. Although we observed an attenuated heart rate (HR),\nhaemodynamic responses to stress remained largely unaffected. Six months of HRT did not\naffect BP, HR, HRV, or haemodynamic responses to stress in hypertensive postmenopausal\nwomen but did result in reduced sensitivity to noradrenaline, a stress hormone, in subcutaneous\narteries. Lower adrenergic response occurred in the resistance arteries of hypertensive\nrats but not in normotensive rats or women. 17b-estradiol relaxed precontracted mesenteric\narteries, due mainly to endothelial release of nitric oxide. We also observed a modulated endothelial\nresponse to acetylcholine following 17b-estradiol treatment in normotensive women\nand hypertensive rats and HRT in hypertensive women.\nIn conclusion, the effects of oestrogen on vascular reactivity and haemodynamics differed between\nhypertensive and nonhypertensive subjects and also according to the type of oestrogen\nused. Decreased BP and HR with 17b-estradiol treatment but not with HRT suggests that 17b-\nestradiol participates selectively in the haemodynamic system. However, the attenuated adrenergic\nvascular response observed in hypertensive subjects independent of oestrogen type may\ncontribute to improved blood fl ow to peripheral tissue even though BP remains unchanged.\nThe clinical importance of the reinforced acetylcholine induced response in normotensive and\nhypertensive women and rats after oestrogen treatment requires further evaluation.\nKey words: adrenergic reactivity, endothelium, haemodynamic, hypertension, oestrogen,\npostmenopausal women, resistance arteries, spontaneously hypertensive rats, stress
Author: Lisa Brandin
Language: English
Subfield: Endocrinology, Diabetes and Metabolism
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W129831519