Noninvasive Characterization of Myocardial Blood Flow in Diabetic, Hypertensive, and Diabetic–Hypertensive Rats Using Spin‐Labeling MRI

Abstract

Objective: Microvascular alterations in the diabetic and hypertensive heart are likely to contribute to heart failure. In this work, myocardial blood flow and left ventricular function were measured in vivo in diabetic, hypertensive, and diabetic–hypertensive rats using MRI methods. Methods: An 8‐week‐duration type 1 diabetes was induced by streptozotocin (STZ) in 8 Wistar‐Kyoto (WKY) rats (STZ) and in 11 spontaneously hypertensive (SHR) rats (STZ‐SHR). Fourteen WKY and 12 SHR served as control and hypertensive groups. Myocardial blood flow quantification was performed using an arterial spin‐labeling MRI method. Left ventricular morphology and function were assessed during the same experiment using cine‐MRI. Results: Respective myocardial blood flow values for each group were 6.4 ± 1.1 (WKY), 6.0 ± 1.9 (STZ), 5.5 ± 1.3 (SHR), and 4.3 ± 0.9 mL· g⁻¹· min⁻¹ (STZ‐SHR). Myocardial blood flow was significantly decreased in STZ‐SHR rats compared with the other groups (p <.05, STZ‐SHR vs. all groups). Cine‐MRI showed morphological alterations in all pathological groups. No alteration of the ejection fraction was observed in the pathological groups. Conclusion: Myocardial blood flow is altered in vivo before any sign of heart failure when rats have type 1 diabetes and hypertension simultaneously. When only one of the pathologies occurs, MBF does not vary significantly.