Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCA202

Poster Communications

Carotid body chemosensitivity correlates with insulinemia and insulin resistance but not with blood pressure in metabolic syndrome patients

S. V. Conde1, J. P. Cunha-Guimaraes1, A. T. Timoteo2, I. Caires1, J. F. Sacramento1, M. J. Ribeiro1, M. Selas2, M. P. Guarino1,3, J. Santiago1, M. Mota-Carmo1,2

1. CEDOC, NOVA Medical School, Faculdade Ciências Médicas, Lisboa, Portugal. 2. Serviço de Cardiologia, Hospital Santa Marta, Centro Hospital Lisboa Central, EPE, Lisboa, Portugal. 3. Escola Superior de Saúde de Leiria- Instituto Politécnico de Leiria, Leiria, Portugal.

We previously showed that the carotid body (CB) is involved in the genesis of metabolic syndrome (MS) since abolishment of its activity prevents and reverses insulin resistance (IR) and hypertension (HT) in metabolic syndrome and type 2 diabetes rat models(1,2). Additionally, we described that CB activity is increased in rodent models of MS(1). Herein, we have investigated if CB chemosensitivity is correlated with insulinemia, insulin resistance and enhanced blood pressure in MS and HT patients. MS and HT patients were recruited at the Cardiology Service, Hospital Santa Marta, Centro Hospitalar Lisboa Central, EPE. Inclusion criteria for MS and HT were those defined by the American Heart Association. The study was approved the Ethics Committee and performed in accordance with the Helsinki Declaration. Written informed consent was obtained from all individuals. Peripheral chemosensitivity was assessed by the Dejours test, which measures the decrease in respiratory frequency (Rf) caused by two breaths of 100%O2. Intima-media thickness, blood pressure and glucose tolerance were evaluated as well as plasma insulin, glucose, HbA1c and lipid profile. Correlations between the variables were obtained by Spearman correlations, stepwise multiple linear regression analysis by SPSS and 2-way ANOVA. Data are means±SD. Thirty-two MS (Age=60.5±11.8 years) and 17 HT patients (Age=67.7±10.4 years) were included. Systolic blood pressure was 150.6±20.8mmHg and 142.5±14.7mmHg in MS and HT patients. Abdominal perimeter was 100.3±12.9cm and 87.8±13.4cm in MS and HT patients (p<0.01). Fasting and 2-hours glucose following OGTT were, respectively, 98.6±41.8mg/dl and 180.2±65.8 mg/dl in MS (p<0.05) and 76.9±21.7 mg/dl and 131.6±22.9 mg/dl in HT. Fasting insulin and HOMA-IR were, respectively, 10.6±7.7 µUI/ml and 2.7±2.7 (p<0.05) in MS and 7.0±4.1 µUI/ml and 1.3±1.1 in HT patients. No significant differences were observed in the lipid profile between MS and HT patients except for HDL-c (p<0.01). Additionally, a non-statistical increase in CB chemosensitivity was found in MS patients, since the % of decrease in Rf produced by 100%O2 is higher than in HT patients (MS= -5.5±12.6 vs HT= 0.4±21.4). Significant correlations were found between CB chemosensitivity and abdominal perimeter (r= -0.47, p<0.05), insulin levels (r=-0.72, p< 0.001) and HOMA-IR (r =-0.54, p< 0.01), in MS patients, but not with the others variables tested. No correlations were found between CB chemosensitivity and all the variables tested in HT patients. This work confirms our preclinical data showing that MS patients exhibit an increased CB chemosensitivity and that insulin levels and sensitivity are inversely correlated with CB activity. Additionally, our data suggest that CB chemosensitivity is not altered in HT.

Where applicable, experiments conform with Society ethical requirements