Vascular function and blood pressure in GH transgenic mice

Area of Science:

• Cardiovascular Physiology
• Endocrinology
• Vascular Biology

Background:

• Acromegaly, a condition linked to cardiovascular disease, is characterized by excess growth hormone (GH).
• Understanding the vascular mechanisms underlying GH-associated hypertension is crucial for managing cardiovascular risks.

Purpose of the Study:

• To investigate vascular function and blood pressure regulation in mice overexpressing bovine growth hormone (bGH).
• To determine if bGH overexpression leads to hypertension and identify underlying structural or functional vascular changes.

Main Methods:

• Mean arterial blood pressure was measured telemetrically in bGH transgenic and control mice under normal and high salt conditions.
• Vascular structure was assessed in perfused hindquarter beds.
• Vascular reactivity and endothelial function were studied in isolated mesenteric resistance arteries.

Main Results:

• bGH transgenic mice exhibited significantly elevated mean arterial blood pressure compared to controls, irrespective of salt intake.
• Perfusion studies revealed a structural narrowing of the hindquarter vascular bed in bGH transgenic mice.
• No significant differences in vascular reactivity or endothelial function were observed between transgenic and control mice.

Conclusions:

• bGH transgenic mice develop a salt-resistant form of hypertension.
• The hypertension is associated with structural narrowing of resistance vasculature.
• Increased peripheral vascular resistance, due to structural changes, is the primary mechanism maintaining hypertension in this model.