Type 2 Diabetic Rats Develop Exercise Pressor Reflex Dysfunction Over Time: New Insight Into Aging With Diabetes

Abstract

Type 2 diabetes Mellitus (T2DM) patients have an augmented sympathetic activity and cardiovascular response to exercise. The exercise pressor reflex, which is evoked by mechanical and metabolic stimuli arising from contracting muscle, and results in an increase in mean arterial pressure and heart rate, may contribute to this augmented response. Studies have shown that the exercise pressor reflex is augmented in several cardiovascular related diseases including T2DM; however, it is not known how the exercise pressor reflex is expressed in aging T2DM rats. Therefore, the purpose of this study was to determine the expression of the exercise pressor reflex with aging in T2DM rats. We measured the exercise pressor reflex in unanaesthetized, decerebrated UC Davis T2DM rats and healthy (CTL) Sprague Dawley rats by statically contracting the hindlimb for 30 s while mean arterial pressure (MAP) and heart rate (HR) were continuously measured. Young (4 mo old) adult T2DM rats (BW: 594±15 g, glucose: 337±73 mg/dl, HbA1c: 7.4±0.3%) and older (12 mo old) adult T2DM rats (BW: 546±26 g, glucose: 549±28 mg/dl, HbA1c: 12.82±0.18%), were compared to adult CTL rats (BW:465±18 g, glucose: 200±14 mg/dl, HbA1c: 4.73±0.1%). We found that the pressor (younger T2DM: ΔMAP=21±5 mmHg, n=4; older T2DM: ΔMAP=39±5 mmHg, n=5; CTL: ΔMAP=17±2 mmHg, n=8; p<0.05) but not cardioaccelerator (younger T2DM: ΔHR=16±4 bpm, n=4; older T2DM: ΔHR=19±7 bpm, n=5; CTL: ΔHR=14±1 bpm, n=8; p>0.05) responses to static contraction were significantly greater in the older adult T2DM, but not in the younger T2DM rats compared to the CTL rats. Developed tension was similar for all group comparisons, p>0.05. We conclude that older T2DM rats develop an augmented exercise pressor reflex to static contraction of the hindlimb, but this hyper‐reactivity is not present in younger T2DM rats. In a population where exercise is typically prescribed as a treatment modality, an augmented exercise pressor reflex can put these individuals at a higher risk for experiencing cardiovascular events while exercising.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.