Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCB218

Oral Communications

Assessing cardiorespiratory and metabolic parameters responses to a mixed meal vs a glucose challenge- a pilot study in healthy volunteers

M. C. Lages1, G. Brito1,3, N. V. Lopes1,3, R. Fonseca-PInto1,3, M. P. Guarino1,2

1. ciTechCare, Polytechnic Institute of Leiria, Leiria, Leiria, Portugal. 2. CEDOC, NOVA Medical School, Lisbon, Portugal. 3. School of Technology and Management, Polytechnic Institute of Leiria, Leiria, Portugal.

The carotid bodies (CB) have been recently implicated in the genesis of metabolic diseases in animal models (1) however, in humans, this mechanism is not well characterized. Acutely, the CBs respond to circulating insulin to increase heart rate, respiratory rate and blood glucose levels (2). Early detection of disturbed insulin action by recording cardiorespiratory and metabolic responses to stimuli like a meal ingestion, is, therefore, a methodology with predictive value potential for metabolic dysfunction. Our aim was to assess physiological changes in CB-related cardiorespiratory and metabolic parameters induced either by ingestion of a mixed meal, or by a glucose challenge, in healthy volunteers. All procedures accorded with current European legislation. Pilot-study tests were performed in five healthy volunteers recruited at Polytechnic of Leiria Health Sciences School. To assess CB activity the volunteers were fed either a mixed meal or a standard glucose tolerance test (OGTT) after a 12 hour fasting period, in different days. The mixed meal had a macronutrient distribution of 65% of carbohydrates, 23% of protein and 12% of lipids. The OGTT consisted of 200 ml of water and 75 g of sugar. Both meals were ingested during a period of 10 minutes. Heart rate (HR), oxygen saturation (SpO2) and respiratory rate (RR) were monitored by means of a real time biosignal acquisition system. Interstitial glucose was monitored continuously. CBView, a MatLab based software, was developed to perform integrated recordings of physiological responses assessed. Results: The plasma glucose excursion curve maximum value was smaller after mixed meal (Δglucose= 20,0 ±10,7mg/dl glucose, latency to steady state= 49± 1min) than OGTT (Δglucose= 29,1±15,1 mg/dl glucose, latency to steady state =54± 5min) and the slope of the linear regression on glucose excursion curves were significantly different (1,03±0,14 mg/dl/min vs 2,34±0,1 mg/dl/min). Heart rate varied after OGTT but not after mixed meal in healthy volunteers (ΔHR= 5,1 ± 0,4 bpm vs -1,3±0,32 bpm, respectively). There were no changes in SpO2 either after mixed meal ingestion or after OGTT. Respiratory Rate increased after OGTT (ΔRR= 3,7 ± 0,2cpm) but not after mixed meal ingestion (ΔRR= 0,55 ± 0,15cpm). In conclusion, in healthy volunteers, ingestion of a mixed meal tested caused detectable, though minor, variations in cardiorespiratory and metabolic parameters compared to the OGTT. Data suggest that meal ingestion may be used as a challenge teste to assess early changes in physiological parameters that may reflect altered CB activity and an increased risk for metabolic dysfunction.

Where applicable, experiments conform with Society ethical requirements