Elevation of plasma CGRP and SP levels in orthopedic patients with fracture neck of femur

Abstract

Calcitonin gene-related peptides (CGRP) is a 37 amino acids peptide that has a proliferative effect on human endothelial cells, and is therefore important for the formation of new vessels and wound healing. As indicated by in vitro and animal studies, CGRP is also a potent vasodilator for cutaneous, cerebral, coronary vessels, a bronchoconstrictor and endocrine regulator. Systemic CGRP increase in patients with soft tissue injuries, chronic illness and sepsis, indicates that CGRP may yet be an important peptides in chronic illness. Although CGRP is a potent vasodilator, systemic vascular resistance does not increase in some patients with high CGRP levels. We questioned whether any changes occur in systemic CGRP levels in patients with one of the most common types of bone fractures especially in the elderly. In order to evaluate further the role of this peptide in these patients, a vasoconstictor (Endothelin-1 [ET]) and another sensory neuropeptide (Substance P [SP]) were measured within 24 h of injury. A sample was obtained on admission (day 1) and within 24 h post admission (day 2) in patients with fracture neck of femur (mean age 77.6, +/- 10 years, n = 20) and compared with healthy controls (51, +/- 26.8 years, n = 20). Peptides and hormones were measured by ELISA techniques. Mean (ng/l) CGRP was elevated in patients (day 1 [314 +/- 195] and day2 [209.2 +/- 150]); compared to controls (68.2 +/-31) P<0.005. Endothelin was non-significantly higher in day-2 (day 1 [28.5 +/-31], day2 [37.4 +/-38], controls [24.2 +/-21]) P = NS. SP maintained higher levels within 24 h after injury (day 1 [85.7 +/- 94], and day2 [80.9 +/- 91.8]) compared to controls, P< 0.05. Furthermore, Elastase (a decisive marker for inflammation and infectious complications) was found to be higher in patients being pronounced in day 2 than in day 1 (day 1 [200 +/-136], day2 [139 +/-118]). Creatine kinase and myoglobin were measured and found to be notably higher in patients. These peptides may be yet another group of cytokines playing significant role in immunologic, inflammatory complications or wound healing in this group of patients.