Thoracoscopic Sympathectomy at the T2 or T3 Level Facilitates Bradykinin-Induced Protein Extravasation in Human Forearm Skin

Role of Bradykinin Type 2 Receptors in Human Sweat Secretion: Translational Evidence Does Not Support a Functional Relationship

Bradykinin increases skin blood flow via a cGMP mechanism but its role in sweating in vivo is unclear. There is a current need to translate cell culture and nonhuman paw pad studies into in vivo human preparations to test for therapeutic viability for disorders affecting sweat glands. Protocol 1: physiological sweating was induced in 10 healthy subjects via perfusing warm (46-48°C) water through a tube-lined suit while bradykinin type 2 receptor (B2R) antagonist (HOE-140; 40 μM) and only the vehicle (lactated Ringer's) were perfused intradermally via microdialysis. Heat stress increased sweat rate (HOE-140 = +0.79 ± 0.12 and vehicle = +0.64 ± 0.10 mg/cm2/min), but no differences were noted with B2R antagonism. Protocol 2: pharmacological sweating was induced in 6 healthy subjects via intradermally perfusing pilocarpine (1.67 mg/mL) followed by the same B2R antagonist approach. Pilocarpine increased sweating (HOE-140 = +0.38 ± 0.16 and vehicle = +0.32 ± 0.12 mg/cm2/min); again no differences were observed with B2R antagonism. Last, 5 additional subjects were recruited for various control experiments which identified that a functional dose of HOE-140 was utilized and it was not sudorific during normothermic conditions. These data indicate B2R antagonists do not modulate physiologically or pharmacologically induced eccrine secretion volumes. Thus, B2R agonist/antagonist development as a potential therapeutic target for hypo- and hyperhidrosis appears unwarranted.

Lumbar sympathectomy reduces vascular permeability, possibly through decreased adenosine receptor A2a expression in the hind plantar skin of rats

BACKGROUND

The effect of lumbar sympathectomy for the treatment of lower limb ischemia remains a matter of controversy.

METHODS

Sprague-Dawley rats were subjected to lumbar sympathectomy, after which Evans blue dye was injected into the hind plantar skin. Extravasation of dye was measured and compared with rats undergoing sham operation. Hind plantar skin was processed for HE staining, immunohistochemistry, and Western blot.

RESULTS

In sympathectomized rats, blue stained areas in hind plantar skin and concentrations of Evans blue were significantly less than that of sham sympathectomy (control) rats, both 2 weeks and 3 months after surgery. Expression of prostaglandin E2, bradykinin, bradykinin B2 receptor, and adenosine triphosphate were not significantly different between the sympathectomized and control groups. Adenosine receptor A2a expression was significantly reduced in the sympathectomized group both 2 weeks and 3 months after surgery.

CONCLUSION

Vascular permeability in the hind plantar skin of rats decreases following lumbar sympathectomy, possibly via reduced expression of adenosine receptor A2a.