Cardiovascular and hormonal responses to cold pressor test in insulin-dependent diabetic adolescents with microalbuminuria

Adynamic response to cold pain reflects dysautonomia in type 1 diabetes and polyneuropathy

Cardiac autonomic neuropathy (CAN), widely assessed by heart rate variability (HRV), is a common complication of long-term diabetes. We hypothesized that HRV dynamics during tonic cold pain in individuals with type 1 diabetes mellitus (T1DM) could potentially demask CAN. Forty-eight individuals with long-term T1DM and distal symmetrical polyneuropathy and 21 healthy controls were included. HRV measures were retrieved from 24-h electrocardiograms. Moreover, ultra-short-term HRV recordings were used to assess the dynamic response to the immersion of the hand into 2 °C cold water for 120 s. Compared to healthy, the T1DM group had expectedly lower 24-h HRV measures for most components (p < 0.01), indicating dysautonomia. In the T1DM group, exposure to cold pain caused diminished sympathetic (p < 0.001) and adynamic parasympathetic (p < 0.01) HRV responses. Furthermore, compared to healthy, cold pain exposure caused lower parasympathetic (RMSSD: 4% vs. 20%; p = 0.002) and sympathetic responses (LF: 11% vs. 73%; p = 0.044) in the T1MD group. QRISK3-scores are negatively correlated with HRV measures in 24-h and ultra-short-term recordings. In T1DM, an attenuated sympathovagal response was shown as convincingly adynamic parasympathetic responses and diminished sympathetic adaptability, causing chronometric heart rhythm and rigid neurocardiac regulation threatening homeostasis. The findings associate with an increased risk of cardiovascular disease, emphasizing clinical relevance.

Higher perceived stress is associated with lower cortisol concentrations but higher salivary interleukin-1beta in socially evaluated cold pressor test

The relationship between subjective stress perception and the objective stress response to acute stress stimuli is not sufficiently understood. The aim of the present study was to test the hypothesis that the neuroendocrine response in socially evaluated cold pressor test (CPT) depends on the extent of perceived stressfulness of the stimulus. The test was performed in 24 healthy male volunteers. Subjective stress perception was assessed using nine visual analog scales. The subjects were divided to low and high stress perception groups according to the median split of the scores. Subjects with high stress perception exhibited slightly lower values of systolic blood pressure and lower overall concentrations of salivary cortisol compared to subjects with low stress perception. Salivary alpha-amylase activity did not show significant changes. Salivary aldosterone decreased in time in subjects with low but increased early after the test in subjects with high stress perception. Interestingly, salivary concentrations of the pro-inflammatory cytokine interleukin-1beta were considerably higher in subjects with high stress perception, particularly immediately before the test. The differences in salivary cortisol and interleukin-1beta were confirmed by the analysis with distress as a continuous covariate. Distress scores correlated negatively with salivary cortisol and positively with interleukin-1beta. The rate pressure product, which is a global measure of energy consumption by the heart, was significantly higher immediately before than after the stress exposure. The present findings show that concentrations of interleukin-1beta are a sensitive component of the stress response at the time before the stressful event.Lay summaryIt is generally expected that higher perceived stressfulness of a stimulus is accompanied by higher activation of stress-related systems. This study evaluating a combined psychosocial and physical stress situation in healthy men provides evidence that individual parameters of the stress response are differently related to perceived stress intensity. Subjects with high stress perception exhibited lower systolic blood pressure and salivary cortisol, higher interleukin-1beta, marginal differences in alpha amylase and aldosterone compared to subjects with low stress perception, which might be important for stress coping.

Sympathetic Neural and Hemodynamic Responses During Cold Pressor Test in Elderly Blacks and Whites

The sympathetic response during the cold pressor test (CPT) has been reported to be greater in young blacks than whites, especially in those with a family history of hypertension. Because blood pressure (BP) increases with age, we evaluated whether elderly blacks have greater sympathetic activation during CPT than age-matched whites. BP, heart rate, cardiac output, and muscle sympathetic nerve activity were measured during supine baseline, 2-minute CPT, and 3-minute recovery in 47 elderly (68 ± 7 [SD] years) volunteers (12 blacks and 35 whites). Baseline BP, heart rate, cardiac output, or muscle sympathetic nerve activity did not differ between races. Systolic and diastolic BP and heart rate increased during CPT (all P<0.001) with no racial differences (all P > 0.05). Cardiac output increased during CPT and ≤ 30 s of recovery in both groups, but was lower in blacks than whites. Muscle sympathetic nerve activity increased during CPT in both groups (both P<0.001); the increase in burst frequency was similar between groups, whereas the increase in total activity was smaller in blacks (P=0.030 for interaction). Peak change (Δ) in diastolic BP was correlated with Δ total activity at 1 minute into CPT in both blacks (r=0.78,P=0.003) and whites (r=0.43,P=0.009), whereas the slope was significantly greater in blacks (P=0.007). Thus, elderly blacks have smaller sympathetic and central hemodynamic (eg, cardiac output) responses, but a greater pressor response for a given sympathetic activation during CPT than elderly whites. This response may stem from augmented sympathetic vascular transduction, greater sympathetic activation to other vascular bed(s), or enhanced nonadrenergically mediated vasoconstriction in elderly blacks.

Correlates of venous catecholamine concentrations in patients with type 1 diabetes during a cold pressor test

In some patients with type 1 diabetes, various physiologic reactions during a cold pressor test (CPT) are impaired. Whether this is caused by diabetic autonomic neuropathy, disturbed secretion of catecholamines, or disturbed blood glucose control is unknown. The authors, therefore, performed CPTs in patients with type 1 diabetes and in control subjects. They measured blood glucose concentrations, insulin concentrations, cardiac autonomic reflexes, and (before and after the CPT) venous catecholamine concentrations and analyzed correlations between these variables. Twenty-two patients with type 1 diabetes (17 men, 5 women; mean age +/- SD, 26.6 +/- 6.5 y; diabetes duration, 7.6 +/- 0.7 y; glycosylated hemoglobin concentration, 7.7 +/- 2.4%) and 35 control subjects with comparable age and gender distributions were studied. Venous catecholamines were measured before and at the end of a 5-minute CPT. In patients with diabetes, only noradrenaline concentrations increased during the CPT, whereas adrenaline concentrations that were already increased at rest did not change. Adrenaline concentrations correlated inversely with insulin concentrations. In control subjects, both adrenaline and noradrenaline increased significantly during the CPT. In both groups, the magnitude of the individual change in catecholamine concentrations was inversely correlated with the respective resting concentration. Changes in catecholamines, cardiovascular reflex tests, and blood glucose concentrations did not correlate with blood pressure changes. The authors conclude that, in patients with diabetes, resting adrenaline concentrations are related to insulin concentrations. Contrary to control subjects, in patients with diabetes, only noradrenaline increased during CPTs. In both groups, changes in catecholamine concentrations after the CPT were inversely related to the respective resting concentrations.