Unlocking a more comprehensive assessment of diet with continuous, chronic blood glucose and complete hemodynamic monitoring in rodents

Abstract

New technology was employed in a novel way to monitor the effect of diet change on continuous blood glucose in addition to standard hemodynamic parameters. A new telemetry implant (HD‐S11‐F2, DSI) enables researchers to collect and transmit data at a different radio‐frequency (18MHz) than the traditional 455KHz implants. While a second frequency allows for social housing and tighter density of research subjects, in this experiment the 18MHz device was paired with a continuous glucose telemetry implant (HD‐XG, DSI) in the same animal. Implantation of two devices in a single animal allowed us to measure blood pressure, ECG, arterial blood glucose, body temperature and activity in a single rat. Six male Sprague Dawley rats were implanted with 2 telemetry implants that each required an arterial site for sensor placement. The HD‐XG sensor was placed in the descending abdominal aorta and the device body was located IP. The HD‐S11‐F2 was inserted in the femoral artery and the catheter tip was advanced to the abdominal aorta (just cranial to the iliac bifurcation), not overlapping the glucose sensor. The HD‐S11‐F2 implant body was placed subcutaneously on the flank. After recovery from surgery, animals were enrolled in a cross‐over designed study to compare the physiologic effects of offering high carbohydrate or low carbohydrate treats after a 12 hour fast. Blood pressure, heart rate and blood glucose values are presented. Marshmallows and mangos were offered as high carbohydrate treats while cheese cubes were offered as the low carbohydrate treat. Approximately 1 hour after the treat offering, the standard rat chow was restored to the cage feeders. The excitement from the technician opening the cage was evident in HR and BP changes associated with that activity. Blood glucose levels from 9–12 hours post‐fast were approximately 92 mg/dl in both groups. Eating marshmallows and mango caused a rapid rise to ~103 mg/dl in ~30 minutes. Eating cheese resulted in a modest rise in blood glucose (~96 mg/dl). These experiments demonstrate a successful surgical approach using two implants to get a more comprehensive picture of whole animal cardiovascular and metabolic physiology.