Honors Program

University Honors

Date of Award

5-2020

Thesis Professor(s)

Krishna Singh

Thesis Professor Department

Biomedical Sciences

Thesis Reader(s)

Suman Dalal

Abstract

Ischemic heart disease is a leading cause of death worldwide. Osteopontin (OPN), a cell-secreted extracellular matrix protein, is suggested to play a cardioprotective role in mouse models of ischemic heart disease. The objective of this study was to examine the role of OPN in modulation of systolic and diastolic functional parameters of the heart following mouse ischemia/reperfusion (I/R) injury. For this, wild-type (WT) and OPN-knockout (KO) mice aged approximately 4 months were subjected to cardiac ischemia for 45 minutes by the ligation of the left anterior descending coronary artery (LAD) followed by reperfusion of LAD by snipping the ligature. Heart function was measured using echocardiography at baseline, 1, 3, 7, 14, and 27 days post-I/R injury. M-mode echocardiographic images were used to calculate % fractional shortening [%FS], % ejection fraction [%EF], end-systolic volume [ESV], and end-diastolic volume [EDV], while pulsed wave Doppler images were used to measure aortic ejection time [AET], isovolumic relaxation time [IVRT], and total systolic time [TST]. Velocity of circumferential fiber shortening (Vcf) was calculated using FS and AET. I/R injury significantly decreased %EF and %FS in both WT and KO groups at all time points (1, 3, 7, 14, and 27 days post-I/R) versus the baseline. However, the decrease in % EF and %FS was significantly greater in KO-I/R group versus WT-I/R at 3, 7, 14 and 27 days post-I/R. I/R-mediated increase in ESV and EDV were significantly greater in KO-MI group versus WT-MI 3 day post-I/R. AET was significantly higher in WT-I/R group 27 days post-I/R versus baseline. However, AET was significantly lower in KO-I/R group 3 and 27 days post-I/R versus WT-I/R. IVRT was significantly higher in KO-I/R group 27 days post-I/R vs baseline. However, IVRT was significantly lower in KO-I/R group 1 day post-I/R vs WT-I/R. TST remained unchanged in WT and KO groups post-I/R versus their respective baseline groups. However, TST was significantly lower in KO-I/R group versus WT-I/R at 3 days post-I/R. Vcf was significantly higher at basal levels in the KO versus WT mice. I/R injury decreased Vcf in both groups versus their baseline at all time-points. These data provide evidence that lack of OPN deteriorates systolic and diastolic functional parameters of the heart following I/R injury, suggesting a cardioprotective role of OPN in myocardial remodeling post-IR.

Publisher

East Tennessee State University

Document Type

Honors Thesis - Withheld

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

Copyright

Copyright by the authors.

Available for download on Saturday, April 30, 2022

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