Effect of morphine on sympathetic nerve activity in humans

Abstract

There are conflicting reports for the role of endogenous opioids on sympathetic and cardiovascular responses to exercise in humans. A number of studies have utilized naloxone (an opioid-receptor antagonist) to investigate the effect of opioids during exercise. In the present study, we examined the effect of morphine (an opioid-receptor agonist) on sympathetic and cardiovascular responses at rest and during isometric handgrip (IHG). Eleven subjects performed 2 min of IHG (30% maximum) followed by 2 min of postexercise muscle ischemia (PEMI) before and after systemic infusion of morphine (0.075 mg/kg loading dose + 1 mg/h maintenance) or placebo (saline) in double-blinded experiments on separate days. Morphine increased resting muscle sympathetic nerve activity (MSNA; 17 +/- 2 to 22 +/- 2 bursts/min; P < 0.01) and increased mean arterial pressure (MAP; 87 +/- 2 to 91 +/- 2 mmHg; P < 0.02), but it decreased heart rate (HR; 61 +/- 4 to 59 +/- 3; P < 0.01). However, IHG elicited similar increases for MSNA, MAP, and HR between the control and morphine trial (drug x exercise interaction = not significant). Moreover, responses to PEMI were not different. Placebo had no effect on resting, IHG, and PEMI responses. We conclude that morphine modulates cardiovascular and sympathetic responses at rest but not during isometric exercise.

Heart Rate Variability: A Novel Modality for Diagnosing Neuropathic Pain after Spinal Cord Injury

“…Less utilized in our cohort, opiates and atypical antidepressants may also alter HRV. Opiates are thought to increase relative vagal tone to the heart and atypical antidepressant medications, namely SNRIs and TCAs, increase systemic sympathetic tone by way of increasing serotonin and norepinephrine concentrations (Carter et al, 2002; Licht et al, 2012; Yekehtaz et al, 2013). Neither GABA analogs nor opiates are known to carry direct cardiac inotropic effects.…”

Celiac Plexus Denudation in Triangle Dissection in Pancreatico Duodenectomy: Perioperative Anesthetic Implications

“…Opioids may modulate cardiovascular and sympathetic response. 4 The patient, on contrary to the effect of celiac plexus block/lysis, had extreme bradycardia. Blockade of visceral sympathetic might shift the homeostatic autonomic balance in the organs towards more parasympathetic predominance with corresponding effects.…”

Effect of Low Dose Remifentanil on Postoperative Pain Relief and Heart Rate Variability in Post-Anaesthesia Care Unit

“…Carter et al (4) showed that morphine increased resting muscle sympathetic nerve activity in healthy volunteers. A few reports have described the effects of remifentanil on HRV or autonomic nervous activity.…”

“…Fujiwara et al (3) showed that spinal anaesthesia induced a decrease of both sympathetic and parasympathetic nerve activities. Several reports describe the effects of opioids on the activity of the sympathetic or parasympathetic nervous system (4)(5)(6)(7)(8). Carter et al (4) examined the effects of morphine on sympathetic nerve activity in humans and found that the intravenous injection of morphine increased sympathetic nerve activity.…”

“…There have been many reports examining the effects of anaesthetic agents or opioids on HRV (2)(3)(4). To ensure stable hemodynamics during anaesthesia, it is important to understand the effects of anaesthetic agents and opioids when measuring HRV.…”