Cardiovascular influences on conditioned pain modulation

Abstract

Conditioned pain modulation (CPM) (ie, diffuse noxious inhibitory controls) is characterized by reduced perception of pain caused by intense pain in a remote body area. The conditioning stimuli used to trigger CPM causes pain, but also important cardiovascular responses. Higher blood pressure has been associated with reduced pain sensitivity. Descending pain inhibitory mechanisms such as CPM could be involved in this relationship. We investigated the associations between CPM and cardiovascular responses during the cold-pressor test (CPT). Heat pain threshold and tolerance were evaluated in 26 (13 men, 13 women) healthy subjects. CPM was evaluated by comparing pain intensity produced by a 120-second heat stimulation before and after a CPT (5 minutes, 7°C). Heart rate, blood pressure, and baroreflex sensitivity were monitored at rest and during CPT to evaluate cardiovascular responses. We observed a positive relationship between resting blood pressure and heat pain tolerance. The CPT caused important heart rate and blood pressure increases. CPT also reduced pain intensity during the subsequent heat pain-stimulus, indicating effective CPM. A significant positive association was observed between CPM magnitude and the increase in blood pressure during the CPT. These results show that resting blood pressure values are related to acute pain tolerance, while descending pain inhibition is associated with increases in blood pressure. The rise in blood pressure caused by the conditioning stimulus is an important factor predicting the extent of endogenous pain inhibition in healthy subjects.

Acute resistance exercise with blood flow restriction in elderly hypertensive women: haemodynamic, rating of perceived exertion and blood lactate

“…This was recently demonstrated (Pinto & Polito, ), in which the authors found that exercise with BFR (three sets, 15 reps, 20% 1RM) showed higher values of rating of perceived exertion and blood lactate than traditional exercise (three sets, eight reps, 65% 1RM without BFR). In this sense, the accumulation of lactate creates a more acid environment, which increases BP via muscle metaboreflex (29) and the pain perception caused by the inflated cuff and by the acid environment increases BP due to stimulation of the central nervous system (Chalaye et al ., ). However, data from the present study showed that rating of perceived exertion and blood lactate was higher in the HI‐RE session than the LI‐BFR session.…”

Hemodynamic response to resistance exercise with and without blood flow restriction in healthy subjects

“…For example, the rating of perceived exertion seems to be high during LI-BFR exercise due to the discomfort of BFR (Wernbom et al, 2006(Wernbom et al, , 2009. The physical discomfort stimulates the central nervous system and consequently blood pressure (Chalaye et al, 2013). In addition, LI-BFR increases blood lactate (Suga et al, 2009), which raises blood pressure via muscle metaboreflex (Rowell, 1997).…”

Relationship Between Blood- and Cerebrospinal Fluid–Bound Neurotransmitter Concentrations and Conditioned Pain Modulation in Pain-Free and Chronic Pain Subjects

“…Their findings raise the possibility that in response to noxious stimuli, descending pain inhibition may be triggered primarily (or solely) by variations in blood pressure. 5,12 In a subsequent study, the same group observed weak systolic blood pressure changes and weak CPM responses among fibromyalgia patients exposed to a CPT challenge. This, again, raises the possibility of a causal link between blood pressure and descending pain inhibition.…”