- Evidence that enhancement of cholinergic tone increases basal plasma levels of calcitonin gene-related peptide in normal man. Trasforini, G., Margutti, A., Vergnani, L., Ambrosio, M.R., Valentini, A., Rossi, R., Portaluppi, F., Degli Uberti, E.C. J. Clin. Endocrinol. Metab. (1994)