Acromegalic Patients Show the Presence of Hypertrophic Remodeling of Subcutaneous Small Resistance Arteries

Abstract

Abstract-Structural alterations of small resistance arteries in patients with essential hypertension (EH) are mostly characterized by inward eutrophic remodeling. However, we have observed the presence of hypertrophic remodeling in patients with renovascular hypertension, as well as in patients with noninsulin-dependent diabetes mellitus, suggesting a relevant effect of humoral growth factors on vascular structure. Growth hormone may stimulate in vitro proliferation of vascular smooth muscle cells. However, no data are presently available about small artery structure in acromegalic patients. Therefore, we have investigated the structure of subcutaneous small arteries in 12 normotensive (NT) subjects, in 12 EH subjects, and in 9 acromegalic patients (APs). All subjects underwent biopsy of the subcutaneous fat; then, small resistance arteries were dissected and mounted on a micromyograph. The normalized internal diameter, media thickness, media-to-lumen ratio, the media cross-sectional area together with remodeling, and growth indices were calculated. Demographic variables were similar in the three groups, except for blood pressure. The media-to-lumen ratio was significantly greater in EH and AP, compared with NT. No difference was observed between EH and AP. The media cross-sectional area was significantly greater in AP compared with EH and with NT. The calculation of remodeling and growth index suggests the presence of eutrophic remodeling in EH (growth index 0%) and of hypertrophic remodeling in AP (growth index 40%). In conclusion, our data suggest the presence of hypertrophic remodeling of subcutaneous small resistance arteries of AP, probably as a consequence of growth-stimulator properties of IGF-1. Key Words: arteries Ⅲ hypertrophy Ⅲ remodeling Ⅲ growth hormone S tructural alterations of small resistance arteries (lumen diameter: 100 to 300 m) 1 of patients with essential hypertension (EH) are mostly characterized by inward eutrophic remodeling (rearrangement of the same wall material around a narrowed lumen). 2,3 At variance, we have observed the presence of hypertrophic remodeling (vascular smooth muscle cell hypertrophy or hyperplasia) in subcutaneous small arteries of patients with renovascular hypertension. 4 Neurohumoral factors are probably involved in the genesis of vascular structural alterations, and growth factors, such as angiotensin II, seem to be able to induce smooth muscle cell hypertrophy. 5,6 Also, patients with noninsulin-dependent diabetes mellitus showed the presence of hypertrophic remodeling of subcutaneous small arteries, 7 suggesting, again, a relevant effect of humoral growth factors on vascular structure. In fact, insulin and insulin-like growth factor-1 (IGF-1) seem to be able to stimulate cardiac and vascular smooth muscle cell growth. 8 A weak but statistically significant correlation between mediato-lumen ratio of subcutaneous small arteries and levels of circulating insulin was observed in patients with diabetes mellitus. 7 It was previously demonstrated that growth hormone ...

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