Key result
Expression of an Ang-(1-7)-producing fusion protein in transgenic rats induced a hypotensive phenotype due to widespread vasodilation and a consequent fall in peripheral resistance.
Why the study?
Activation of the ACE2/Ang-(1-7)/MAS receptor pathway of the RAS induces protective mechanisms, motivating the characterization of the cardiovascular phenotype of a new transgenic rat line expressing an Ang-(1-7)-producing fusion protein.
A novel transgenic rat model expressing an Ang-(1-7)-producing fusion protein exhibits a hypotensive phenotype driven by widespread vasodilation, offering a new tool for pathophysiological studies.
Supports Ang-(1-7) pathway research in hypertension models; leaves open human translation.
Activation of the angiotensin (Ang)-converting enzyme (ACE) 2/Ang-(1-7)/MAS receptor pathway of the renin-angiotensin system (RAS) induces protective mechanisms in different diseases. Herein, we describe the cardiovascular phenotype of a new transgenic rat line (TG7371) that expresses an Ang-(1-7)-producing fusion protein. The transgene-specific mRNA and the corresponding protein were shown to be present in all evaluated tissues of TG7371 with the highest expression in aorta and brain. Plasma Ang-(1-7) levels, measured by radioimmunoassay (RIA) were similar to control Sprague-Dawley (SD) rats, however high Ang-(1-7) levels were found in the hypothalamus. TG7371 showed lower baseline mean arterial pressure (MAP), assessed in conscious or anesthetized rats by telemetry or short-term recordings, associated with increased plasma atrial natriuretic peptide (ANP) and higher urinary sodium concentration. Moreover, evaluation of regional blood flow and hemodynamic parameters with fluorescent microspheres showed a significant increase in blood flow in different tissues (kidneys, mesentery, muscle, spleen, brown fat, heart and skin), with a resulting decrease in total peripheral resistance (TPR). TG7371 rats, on the other hand, also presented increased cardiac and global sympathetic tone, increased plasma vasopressin (AVP) levels and decreased free water clearance. Altogether, our data show that expression of an Ang-(1-7)-producing fusion protein induced a hypotensive phenotype due to widespread vasodilation and consequent fall in peripheral resistance. This phenotype was associated with an increase in ANP together with an increase in AVP and sympathetic drive, which did not fully compensate the lower blood pressure (BP). Here we present the hemodynamic impact of long-term increase in tissue expression of an Ang-(1-7)-fusion protein and provide a new tool to investigate this peptide in different pathophysiological conditions.
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Alves et al. (2021) studied this question. Ang-(1-7)-producing fusion protein expression (TG7371 rats) vs. Control Sprague-Dawley (SD) rats was evaluated on Hemodynamic phenotype (mean arterial pressure, regional blood flow, total peripheral resistance). Expression of an Ang-(1-7)-producing fusion protein in transgenic rats induced a hypotensive phenotype due to widespread vasodilation and a consequent fall in peripheral resistance.
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