Neurotransmitter and neuropeptide control of the bone resistance vasculature

Abstract

Adequate bone blood flow is requisite for bone growth and repair. Regulation of bone blood vessels via the nervous system may provide a mechanism for the control of bone perfusion. We assessed whether the femoral principal nutrient artery (PNA), the primary conduit for blood flow to long bones, is controlled by various neurotransmitters and neuropeptides. Femoral PNAs from male Wistar rats (4 mon) were dissected and cannulated to assess vasomotor properties to increasing concentrations of neuropeptide Y (NPY; 0.125–1.000 mg/ml), Adenosine triphosphate (ATP; 0.78–50.00 μM/ml), mATP (4.95×10−4 – 4.95×10−8 M), norepinephrine (NE; 10−9–10−4 M), phenylephrine (PE; 10−9–10−4 M), clonidine (CLO; 10−9–10−6 M), vasoactive intestinal peptide (VIP; 10−10–10−4 M), calcitonin gene related peptide (CGrP; 10−10– 10−4 M) and Substance P (Sub P; 10−10–10−4 M). Interestingly, the femoral PNAs vasoconstricted to NPY, ATP and mATP (range = 31–57%). Additionally, vasoconstriction to NE and PE was ~77%, while CLO elicited only 33% vasoconstriction. Peak vasodilatations between 33–54% were observed to VIP, CGrP and Sub P. Data from the current study illustrate a potential role for these neurotransmitters and neuropeptides in the regulation of the bone resistance vasculature. Thus, the nervous system may provide a means of controlling bone blood flow during bone growth and repair. Supported by UTA REP grant 10466.