Chronic femoral artery occlusion augments exercise pressor reflex in decerebrated rats

Abstract

In decerebrated rats, we determined the pressor and cardioaccelerator reflex responses to static contraction of hindlimb muscles whose femoral arteries were either occluded 72 h before contraction, occluded 3 min before contraction, or freely perfused. We found that the pressor reflex arising from the limb whose femoral artery was occluded for 72 h before contraction (32 +/- 5 mmHg, n = 16) was significantly higher than the pressor reflex arising from the contralateral freely perfused limb (15 +/- 3 mmHg, n = 16, P < 0.001) or than that arising from the contralateral limb whose femoral artery was occluded for only 3 min (17 +/- 4 mmHg, n = 16, P < 0.001). Moreover, the pressor reflex arising from the limb whose femoral artery was occluded for 3 min before the start of contraction was not significantly different than that arising from the contralateral freely perfused limb (n = 16, P = 0.819). The pressor component of the reflex arising from the limb whose femoral artery was occluded for 72 h was not changed by transient receptor potential vanilloid (TRPV) 1 receptor blockade with iodo-resiniferatoxin (n = 15, P = 0.272), although the cardioaccelerator component was significantly reduced (P = 0.005). In addition, the pressor response evoked by capsaicin injection in the femoral artery of the 72-h occluded limb was more than double that evoked from the freely perfused limb (P = 0.026). We conclude that chronic (i.e., 72 h) but not acute (3 min), femoral arterial occlusion augments pressor reflex arising from contraction of hindlimb muscles and that TRPV1 receptors play little role in this augmentation.

Tetrodotoxin-resistant voltage-dependent sodium channels in identified muscle afferent neurons

“…However, one model of peripheral vascular disease, 72-h muscle ischemia, failed to reduce the effect of TTX to block the exercise pressor reflex (Tsuchimochi et al 2011). While this model does increase cardiovascular responses to muscle contraction (Tsuchimochi et al 2010), it is possible that 72 h is insufficient to produce changes in Na V channel distribution in Group III and IV neurons. Chronic nerve injury models that do produce such changes are typically measured 7-10 days after injury (Gold et al 2003;Jarvis et al 2007).…”

Inhibition of cyclooxygenase attenuates the blood pressure response to plantar flexion exercise in peripheral arterial disease

“…The 30-mg dose was chosen because it is effective at reducing postoperative pain (1). We suspected that stimulation of muscle afferents would occur at lower prostanoid levels compared with pain (18,39). A 30-min waiting period occurred after injection to ensure the drug was sufficiently active in the blood (26), and a blood sample was then obtained for the measurement of thromboxane B 2 (stable marker of thromboxane A2) and 6-keto-PGF1␣ (stable marker of prostacyclin, Penn State Core Endocrine Laboratory).…”

Effects of peripheral and spinal κ-opioid receptor stimulation on the exercise pressor reflex in decerebrate rats

“…These interneurons, in turn, project initially to neurons in the ventrolateral medulla and the nucleus of the solitary tract (9, 29), and eventually to autonomic preganglionic neurons. The functional consequences of activating the exercise pressor reflex during exercise include increases in arterial blood pressure, heart rate (HR), and ventilation, all of which contribute to the increases in exercising skeletal muscle blood flow and O 2 delivery (1, 2, 27).In cats, dogs, and rats, acute or chronic muscle ischemia exaggerates the exercise pressor reflex (8,19,27,32,36). Our laboratory recently reported, for example, that the reflex is larger in rats whose femoral arteries were ligated 72 h before the start of the experiment than it was in rats whose femoral arteries were freely perfused (36).…”

“…In cats, dogs, and rats, acute or chronic muscle ischemia exaggerates the exercise pressor reflex (8,19,27,32,36). Our laboratory recently reported, for example, that the reflex is larger in rats whose femoral arteries were ligated 72 h before the start of the experiment than it was in rats whose femoral arteries were freely perfused (36).…”

“…Our laboratory recently reported, for example, that the reflex is larger in rats whose femoral arteries were ligated 72 h before the start of the experiment than it was in rats whose femoral arteries were freely perfused (36). When the femoral artery of rats is ligated, the collateral circulation provides sufficient blood flow to the hindlimb muscles when they are at rest, but does not provide sufficient flow when they are exercising (30,40).…”