Blood pressure in Warmblood horses before and during a euglycemic-hyperinsulinemic clamp.

Katarina E A Nostell,Johan T Bröjer,Sanna S Lindåse

doi:10.1186/s13028-016-0247-y

Katarina E A Nostell, Johan T Bröjer + Show 1 more

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https://doi.org/10.1186/s13028-016-0247-y

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Abstract

BackgroundInsulin resistance (IR) in humans is related to hypertension and impaired vasodilation. Insulin administration has been shown to lower blood pressure both in insulin resistant as well as in insulin sensitive individuals. The aim of the study was to investigate the association between insulin sensitivity and alterations in blood pressure in healthy horses before and after a euglycemic-hyperinsulinemic clamp (EHC). A 3-h EHC was performed in 13 healthy horses (11 mares, 2 geldings). Blood samples for measurement of plasma glucose and insulin were collected before the start of the EHC, every 10 min during the EHC and immediately after the EHC. Mean, systolic- and diastolic blood pressure was measured before and during the final 10 min of the EHC using an indirect high-definition oscillometric monitor (HDO, horse model) applied to the middle of the coccygeal artery. Five consecutive measurements were made in each horse and on each occasion. Insulin and glucose data from the EHC were used to calculate the mean rate of glucose disposal per unit of insulin during steady state (M/I ratio). Insulin resistance was defined as a M/I ratio <5 mg/kg/min/mUL (Lindåse et al. in Am J Vet Res 77:300–309, 2016).ResultsInsulin administration decreased systolic, diastolic and mean arterial pressure in all horses. The M/I ratio for all horses was negatively correlated with the decrease in systolic blood pressure (r2 = 0.55, P = 0.004) and mean arterial pressure (r2 = 0.31, P = 0.048) but not diastolic blood pressure (r2 = 0.12, P = 0.26). Eight horses were defined as insulin resistant (IR) and five horses had normal insulin sensitivity. The five horses with normal insulin sensitivity showed a greater decrease in systolic blood pressure (−17.0 ± 7.4 vs. −3.4 ± 4.6 mmHg, P = 0.001) and MAP (19.2 ± 14.7 vs. 6.9 ± 8.7 mmHg, P = 0.04) than IR horses. There was no difference in the decrease in diastolic blood pressure between groups (16 ± 12.8 vs. 8.9 ± 12.1 mmHg, P = 0.17).ConclusionsThis study indicates that there is a relationship between insulin sensitivity and systolic and MAP in horses. However, studies on a larger number of horses are needed to confirm this association.

Highlights

Insulin resistance (IR) in humans is related to hypertension and impaired vasodilation
The M/I ratio for all horses was negatively correlated with the decrease in systolic blood pressure (r2 = 0.55, P = 0.004) and mean arterial blood pressure (MAP) (r2 = 0.31, P = 0.048) but not diastolic blood pressure (r2 = 0.12, P = 0.26), see Fig. 1
The M value for all horses showed a negative correlation with the decrease in systolic- (r2 = 0.37, P = 0.027) and MAP (0.31, P = 0.049) but not diastolic blood pressure (r2 = 0.08, P = 0.36), Eight horses were defined to be insulin resistant [M/I ratio 4.2 ± 0.6/(mU/L)] and five horses were defined as insulin sensitive [M/I index 7.2 ± 1.0/(mU/L)]

Summary

Introduction

Insulin resistance (IR) in humans is related to hypertension and impaired vasodilation. Insulin activates the renin-angiotensinaldosterone system (RAAS) and thereby increases the retention of sodium and water in the distal tubuli of the nephron [1, 3] This helps to balance blood pressure during normal physiological conditions. There are increasing evidence that obesity, which is often associated with IR, further stimulates the RAAS and causes an increased retention of sodium and water which in turn increases the circulating blood volume [1, 3]. All of this promotes a rise in blood pressure and in the long run causes hypertension

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