Coronary microvascular dysfunction in postmenopausal minipigs with multiple risk factors

Abstract

Coronary microvascular angina occurs in both men and women, however, the majority of patients are postmenopausal women with multiple cardiovascular risk factors, such as diabetes mellitus (DM), chronic kidney disease (CKD) and dyslipidemia. No treatment is available for coronary microvascular dysfunction, requiring more in depth knowledge on the mechanisms underlying this syndrome in this expanding group of patients. Here we studied microvascular function in vivo and and in vitro in isolated small coronary arteries, in postmenopausal miniswine with multiple cardiovascular risk factors. DM (streptozotocin), hypercholesterolemia (HC, high fat, high sugar diet), CKD (renal artery embolization) and menopause (OVX) were induced in 5 adult female minipigs (1.5-2 years old, ±40kg, DM+HC+CKD+OVX) for 6 months, while 11 healthy female minipigs matched for age and weight, on normal pig chow served as controls (Control). At sacrifice, coronary flow reserve (CFR) in response to intracoronary infusion of adenosine was measured under anesthesia, and endothelium-dependent response to bradykinin in the presence and absence of eNOS blockade with LNAME, were studied in vitro in isolated small coronary arteries. 6 months of sustained hyperglycemia (17.5±1.0 in in DM+HC+CKD+OVX vs 8.2±0.9 mmol/l in Control), hypercholesterolemia (15.4±2.0 vs 1.7±0.1 mmol/l) and renal dysfunction (plasma total protein: 84±3 vs 72±1 g/l) were accompanied by systemic inflammation (TNFalpha: 62±7 vs 47±1 pg/ml, all p<0.05 by t-test). Coronary flow reserve was significantly reduced in animals with multiple risk factors (3.4±0.4 in DM+HC+CKD+OVX) as compared to the healthy animals (4.9±0.3 in Control, p<0.05). In vitro, coronary small arteries from DM+HC+CKD+OVX animals showed impaired endothelium-dependent vasodilation to bradykinin, which was mediated by a loss of nitric oxide. Conclusion: Postmenopausal minipigs with multiple risk factors, displayed severe coronary microvascular dysfunction as evidenced by a significantly reduced coronary flow reserve and endothelial dysfunction. The latter was characterized by a marked loss of nitric oxide. Such perturbations may contribute to reduced myocardial perfusion that is often observed in postmenopausal women with multiple cardiovascular risk factors. Funding: Grant 2020B008 RECONNEXT. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.