Читать книгу Metabolic Syndrome Consequent to Endocrine Disorders - Группа авторов - Страница 20

Achievement of peak cardiac mass remains under the influence of GH in young adulthood and adolescence. Direct and indirect GH action via IGF-1 causes increased synthesis of myosin light chain-2 and troponin I, leading to cardiac cell growth. IGF-1 is also known to increase intra-cellular calcium and calcium sensitivity, leading to increased cardiac contractility [72]. GHD causes myocardial hypokinesis with loss of normal response to exercise [73, 74]. In adults with childhhood-onset GHD cardiac mass is significantly reduced. Previous echo studies in younger patients, receiving higher doses of GH have clearly demonstrated increase in left ventricular mass within one year of GHRT [75–77]. Recently this was demonstrated in the middle-aged GHD patients using magnetic resonance imaging [76, 78]. Study in older GHD patients demonstrated no difference suggesting that other factors than GH, such as BP, have a more significant effect on cardiac mass in older individuals.

Anabolic effects of GHRT on LV mass seem to be short-lasting (1–2 years of GHRT) and disappear soon after discontinuation of treatment or return to normal after 2 years of long-term (10 years) GHRT. However, decrease in diastolic BP and improvement of diastolic filling seem to persist during long-term (7 years) GHRT [32].