This study sought to determine which tachykinin receptors were involved in contractile responses of circular muscle to tachykinins infused into isolated segments of canine ileum. Selective agonists for neurokinin receptors NK1 and NK2 as well as for substance P (SP) and neurokinin A (NKA) were infused, and selective antagonists against NK1, NK2, and NK3 receptors were tested. The responses to a submaximal concentration of NKA were reduced by a selective NK2 antagonist, SR-48968, and abolished by a combination of this antagonist with an NK1 antagonist, either CP-96,345 or RP-67580. The selective NK2 agonist, [Nle10]NKA-(4-10), had low potency. We concluded that NKA acted on typical NK2 receptors and that is action was potentiated by its additional action on NK1 receptors. Neither the contractile responses to SP nor those to [Sar9,Met(O2)11]SP given in submaximal concentrations were inhibited by CP-96,345 or RP-67580, either alone or together with SR-48968. Indeed, the two NK1-selective antagonists potentiated responses to the selective NK1 agonist, [Sar9,Met(O2)11]SP, an effect attributed to previously demonstrated prejunctional inhibitory action of the agonist. The selective NK3 agonist, succinyl-[Asp6,N-Me-Phe8]SP-(6-11), was not effective as a contractile agent, even after block of nitric oxide synthase with N omega-nitro-L-arginine. The selective NK3 antagonist, R-487, was also ineffective in blocking responses to SP. Studies with an antagonist to H1 histamine receptors suggested that contractile actions of SP did not involve histamine release from mast cells. We concluded that, in addition to typical NK1 and NK2 receptors activated by NKA and a prejunctional inhibitory receptor activated by SP and [Sar9,Met(O2)11]SP, another tachykinin receptor existed on canine ileum to initiate contractions. It is not a typical NK1, NK2, or NK3 receptor.

IntroductionRubber band ligation (‘banding’) is a common approach for the management of symptomatic haemorrhoids. However, up to 90% of patients experience postprocedural pain, and there is no consensus regarding the optimal analgesic strategy. In practice, patients may receive submucosal local anaesthetic, pudendal nerve block or routine periprocedural analgesia. The aim of this study is to compare the efficacy of submucosal local anaesthetic, pudendal nerve block and routine analgesia for postprocedural pain in patients undergoing haemorrhoid banding.Methods and analysisThis is a multicentre, prospective, three-arm, double-blind randomised controlled trial of adults booked for haemorrhoid banding. Participants will be randomised to one of three groups in a 1:1:1 ratio: (1)submucosal bupivacaine injection; (2) pudendal nerve ropivacaine injection and (3) no local anaesthetic. The primary outcome is patient reported postprocedural pain (scored 0–10) from 30 min to 2 weeks. Secondary outcomes include postprocedural analgesia use, time to discharge, patient satisfaction, time to return to work and complications. A sample size of 120 patients is required to achieve statistical significance.Ethics and disseminationThis study received Human Research Ethics Approval from the Austin Health Human Research Ethics Committee (March 2022). Trial results will be submitted to a peer-reviewed journal, and presented at academic meetings. A summary of the trial results will be made available to study participants on request.Trial registration numberACTRN12622000006741p.

Tachykinins induce motor activity in the canine ileum, and their mechanism of excitation may include inhibition of the release of a nonadrenergic, noncholinergic inhibitor, for which vasoactive intestinal polypeptide (VIP) is a candidate. Both substance P and neurokinin A produced a dose-dependent increase in ileal contractility with no significant change in VIP output. The highly selective NK1 agonist [Sar9, Met(O2)11]substance P and the highly selective NK2 agonist [Nle10]neurokinin A (4-10) also increased motor activity in the absence of any change in VIP released. These data suggest that the tachykinins produce motor activity in the canine ileum via a mechanism that does not involve changes in VIP output but may involve excitation through both NK1 and NK2 receptors.

Background Significant barriers exist to surgeons being good parents and parents being good surgeons, and these barriers are heightened for women. Considering the gender balance now present in postgraduate medical schools, it is critical that these barriers are overcome if surgery is to attract and retain applicants. This study aimed to investigate patterns of parenthood in surgery, explore associated attitudes and experiences, and identify barriers and solutions within an Australian and New Zealand context. Methods Surgeons and trainees were invited to participate in a survey and focus groups. Quantitative results were described, and textual responses and focus group transcriptions were analysed thematically. Results There were 261 survey respondents (62.8 per cent women, 37.2 per cent men) and six focus groups (34 participants). Of the survey respondents, 79.6 per cent of women and 86.5 per cent of men had children. Women were more likely to time childbirth around training or work, and most respondents without children attributed this to their career. Tensions between parenthood and surgery engendered guilt for surgeon-parents. Parenthood was often the ‘elephant in the room’ in training and employment discussions. Breaking the silence around parenthood and surgery made it more acceptable, normalising positive behaviour changes. The major barrier to parenthood and surgery was the lack of flexible training opportunities. Participants called for top-down establishment of mandated, stand-alone, permanent part-time training positions. Conclusion Many barriers to parenthood in surgery are created by rigid workplace and professional structures that are reflective of male-dominated historical norms. A willingness to be flexible, innovative and rethink models of training and employment is central to change.

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