Subject(s)
Continuity of Patient Care/organization & administration , Hospital-Physician Relations , Physicians, Family/statistics & numerical data , Ambulatory Care Information Systems , Communication , Consultants , Continuity of Patient Care/standards , Cooperative Behavior , Denmark , Diffusion of Innovation , Institutional Practice , Primary Health Care/organization & administration , Quality Assurance, Health Care/organization & administration , Referral and ConsultationABSTRACT
The in vitro contractile effect of neuropeptide Y (NPY) on rat myometrial strips was for the first time demonstrated and characterised, and the EC50 value estimated to be 267 +/- 87 nM. This effect is presumably mediated by the NPY1 receptor being responsible for postsynaptic effects throughout the peripherial nervous system, thus indicating a direct uterotonic effect of NPY. Further, the effect was demonstrated to the dependent on extracellular Ca2+. Short-term exposures to NPY markedly desensitized the tissue affecting subsequent responses to NPY as well as to oxytocin (OT). This desensitization was time and concentration-dependent, but lasted less than three hours. However, long-term infusions of NPY for 5 days increased to response to both NPY and OT. Long-term infusions of OT caused a marked decrease of the NPY response, and it is concluded that common pathways for up and down regulation of the myometrial responsiveness to several peptide hormones may exist.
Subject(s)
Muscle Contraction/drug effects , Myometrium/physiology , Neuropeptide Y/pharmacology , Animals , Calcium/metabolism , Dose-Response Relationship, Drug , Down-Regulation , Female , Neuropeptide Y/administration & dosage , Neuropeptide Y/analogs & derivatives , Neuropeptide Y/metabolism , Oxytocin/pharmacology , Rats , Rats, Wistar , Receptors, Neuropeptide Y/metabolism , Verapamil/pharmacologyABSTRACT
Substance P and the two other mammalian tachykinins, neurokinin A and B, are accepted to have direct regulating effects at the anterior pituitary level. We have examined the effects of substance P (SP) and neurokinin B (NKB), alone and in combination, on prolactin release from cultured anterior pituitary cells grown on collagen-coated micro beads and placed in a perfusion system. Prolactin (Prl) secretion was observed within 25 s after exposure to either secretagogue and reached a maximum within 60-80 s. Furthermore, the prolactin response induced by SP and NKB was dose-dependent. Prl secretion remained constant for up to 4 h when SP or NKB were perifused and then fell gradually towards basal levels. Simultaneous addition of submaximal concentrations of SP and NKB resulted in an additive response compared with the responses of either secretagogue alone. Continuous (8 h) perifusion with SP did not prevent a normal prolactin response by NKB or TRH. These results indicate that the tachykinins, substance P and neurokinin B, release Prl from perifused female rat anterior pituitary cells by interaction with two different receptors, possibly the NK1 and NK3 tachykinin receptor subtypes.
