ABSTRACT
Three types of tachykinin receptors, NK(1), NK(2)and NK(3), have been described to preferentially interact with substance P (SP), neurokinin A (NKA) and neurokinin B (NKB) respectively. Experimental evidence indicates that SP and NKA modulate the activity of inflammatory and immune cells, including mononuclear ones, and points to their involvement in lung pathophysiology. We previously reported that NK(1)and NK(2)receptors are present on monocytes (MO) isolated from healthy donors or rheumatoid patients - a greater sensitivity to NK(2)receptor stimulation was observed in the latter condition. This study evaluated the effects of SP and NKA, as well as NK(1)and NK(2)selective agonists and antagonists, on MO obtained from healthy volunteers, healthy smokers or patients with interstitial lung diseases (e.g. sarcoidosis and idiopathic pulmonary fibrosis). Superoxide anion (O(2)(-)) production was chosen as a parameter of cell activation. SP and NKA dose-dependently evoked O(2)(-)production from MO in all the conditions evaluated, their effects being competitively antagonized by selective antagonists (CP 96 345 and MEN 10 627, respectively). When selective NK(1)and NK(2)agonists were used, [Sar(9)Met(O(2))(11)]SP, a selective NK(1)agonist, induced a more than doubled O(2)production in MO obtained from patients with interstitial lung diseases as compared to healthy volunteers, whereas MO isolated from healthy volunteers were more sensitive to NK(2)receptor stimulation.
Subject(s)
Lung Diseases, Interstitial/blood , Monocytes/physiology , Receptors, Neurokinin-1/blood , Receptors, Neurokinin-2/blood , Receptors, Neurokinin-3/blood , Smoking/blood , Tachykinins/pharmacology , Adult , Aged , Cells, Cultured , Female , Humans , Male , Middle Aged , Neurokinin A/analogs & derivatives , Neurokinin A/pharmacology , Peptide Fragments/pharmacology , Pulmonary Fibrosis/blood , Reference Values , Sarcoidosis/blood , Substance P/analogs & derivatives , Substance P/pharmacology , Superoxides/bloodABSTRACT
The blood concentration of three representative endothelin and four neurokinin receptor antagonists were monitored both at the portal and jugular vein of rats 30, 60 and 90 min after oral administration. Peptide-derived structures, in the size range tetra-pentapeptides, were shown to be absorbed in the reverse order of their log P values, to be weakly metabolized in the first hepatic transit and to maintain high blood levels during the observation time. These interesting results obtained by a simple and convenient UV assay, stress once again the importance of monitoring oral absorption early in the process of peptide drug design.
