Data presented at a conference on experimental biology (Washington, DC) can shed light on the causes of increased cardiovascular risk with each subsequent pregnancy. Laboratory studies have shown that repeated pregnancies lead to persistent violations of the regulation of the cardiovascular system due to changes in the structure of the vessels and endothelial function.

Scientists from the University of Alberta (Edmonton, Canada), suggested that the causes of increased cardiovascular risk in reintroducing women are similar. According to epidemiological studies, repeated pregnancies are associated with an increase in this risk, but the cause of this phenomenon is still unclear. Dr. Susan Kaufman and her colleagues studied the response to intravenous infusions of phenyladrenaline (a vasoconstrictor similar in effect to epinephrine) and to acute stress (compressed air flow for 10 seconds) in laboratory animals-rats that several times produced offspring and never gave birth.

It turned out that the former are more sensitive to phenyladrenaline and stress: the vasoconstrictor effect was more pronounced in them, at the same heart rate. Consequently, in repeatedly given mice, peripheral vascular resistance was increased. In addition, their isolated mesenteric arteries were more sensitive to phenyladrenaline and less elastic. These differences were endothelium-dependent, since after removal of the endothelium, they disappeared.

Although the arterial pressure at rest was the same in both groups, the response of re-borne animals to stress and stress hormones was more pronounced - in part due to the restriction of the mesenteric vessels. According to the authors, this leads to transient and then to chronic stress-induced increases in total peripheral resistance and post-loading on the heart. Perhaps this is due to hormonal changes in the body after pregnancy - in particular, with a decrease in plasma levels of prolactin and estrogen.

Medicus. En.

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