ATP as a sympathetic neurotransmitter

ATP has been shown to be a sympathetic neurotransmitter in blood vessels. However, its relative importance has been shown to be influenced by the experimental conditions employed such as alteration of the vascular tone. Thus the main aim was to raise the tone of vascular preparations and to further examine sympathetic neurotransmission in these preparations. Porcine whole mesenteries were perfused with physiological buffer and changes in pressure recorded or different sized mesenteric arteries were isolated and set up for isometric recording. Responses to electrical field stimulation (EFS) were obtained under basal and raised tone conditions induced by U46619, a thromboxane A2 mimetic. The nature of the neurotransmitters involved in the mediation of the electrically-evoked responses was assessed using an α1-adrenoceptor antagonist, prazosin and/or the P2X receptor desensitizing agent, α,β-methyleneATP, an α2-adrenoceptor RX811059 antagonist, and a neuropeptide Y Y1 receptor antagonist BIBP3226. In separate experiments, responses to nerve stimulation were investigated in rat mesenteric small arteries pressurized to 90 mmHg. The effects of a selective α1-adrenoceptor antagonist, YM-12617, and selective P2X1 receptor antagonist, NF-449, on the electrically-evoked response were determined. Under basal tone conditions the electrically-evoked contractile responses in porcine whole mesenteric bed and isolated arteries were exclusively mediated by noradrenaline (NA) since they were inhibited by prazosin. However, under conditions of raised tone, the electrically-evoked responses were enhanced and a role for ATP was evident since these responses were sensitive to α,β-methyleneATP. Responses to exogenous NA and α,β-methyleneATP were also enhanced at raised tone indicating a postjunctional mechanism of enhancement. Nifedipine attenuated the enhanced responses to EFS and α,β-methyleneATP suggesting a possible role for L-type calcium channels in the mediation of the enhanced responses. In rat pressurised mesenteric arteries the electrically-evoked vasocontractile responses were sensitive to YM-12617 and NF-449, indicating that NA and ATP were involved in the mediation of these responses. Raising tone with U46619 in these arteries enhanced the electrically-evoked contractile response; under these conditions responses were sensitive to both YM-12617 and NF-449. The present study supports the observation that ATP becomes a more important sympathetic neurotransmitter under conditions of raised tone in contrast to when tone is absent. In porcine mesenteric vascular preparations NA predominates as the main sympathetic neurotransmitter under conditions of basal tone. However, when tone was raised the responses were enhanced and a role for ATP became evident

Attitudes of Middle Eastern Societies towards Organ Donation: The Effect of Demographic Factors among Jordanian Adults

Background: Organ donation gives thousands of patients a renewed chance at living full and active lives. Unfortunately, the need for organs does not match their availability. This study aims to analyze the effect of demographic factors on the knowledge and awareness of the Jordanian society towards organ donation. Methods: This cross-sectional study was conducted using a self-administered online questionnaire. We included 1041 adult Jordanians from all the governorates of the Hashemite Kingdom of Jordan. Results: Of the 1041 participants, only 124 (11.9%) had previously singed organ donation card. Overall, 827 (79.4%) were fully accepting organ donation. Among 782 participants in the medical field, 639 (81.7%) fully accepted organ donation, compared to 188 out of 259 (72.6%) in the non-medical field (p= 0.002), with no significant effect of any demographic factor on the willingness to sign organ donation card. There was significant difference in the acceptance of donation from brain dead donors (p< 0.001), with participants from medical field and male participants having higher acceptance rates when compared with non-medical and female participants, respectively. The main barrier for organ donation was found to be the desire to be buried as a whole (58.2%), followed by traditional beliefs (47.4%), and family refusal (42.2%). Conclusions: In conclusion, an educational strategy can improve organ donation awareness from an early age by spreading actionable information through social media and conducting nationwide public campaigns

Raised tone reveals ATP as a sympathetic neurotransmitter in the porcine mesenteric arterial bed

The relative importance of ATP as a functional sympathetic neurotransmitter in blood vessels has been shown to be increased when the level of preexisting vascular tone or pressure is increased, in studies carried out in rat mesenteric arteries. The aim of the present study was to determine whether tone influences the involvement of ATP as a sympathetic cotransmitter with noradrenaline in another species. We used the porcine perfused mesenteric arterial bed and porcine mesenteric large, medium and small arteries mounted for isometric tension recording, because purinergic cotransmission can vary depending on the size of the blood vessel. In the perfused mesenteric bed at basal tone, sympathetic neurogenic vasocontractile responses were abolished by prazosin, an α1- adrenoceptor antagonist, but there was no significant effect of α,β-methylene ATP, a P2X receptor-desensitizing agent. Submaximal precontraction of the mesenteric arterial bed with U46619, a thromboxane A2 mimetic, augmented the sympathetic neurogenic vasocontractile responses; under these conditions, both α,β-methylene ATP and prazosin attenuated the neurogenic responses. In the mesenteric large, medium and small arteries, prazosin attenuated the sympathetic neurogenic contractile responses under conditions of both basal and U46619-raised tone. α,β-Methylene ATP was effective in all of these arteries only under conditions of U46619- induced tone, causing a similar inhibition in all arteries, but had no significant effect on sympathetic neurogenic contractions at basal tone. These data show thatATP is a cotransmitter with noradrenaline in porcine mesenteric arteries; the purinergic component was revealed under conditions of partial precontraction, which is more relevant to physiological conditions

ATP as a sympathetic neurotransmitter

ATP has been shown to be a sympathetic neurotransmitter in blood vessels. However, its relative importance has been shown to be influenced by the experimental conditions employed such as alteration of the vascular tone. Thus the main aim was to raise the tone of vascular preparations and to further examine sympathetic neurotransmission in these preparations. Porcine whole mesenteries were perfused with physiological buffer and changes in pressure recorded or different sized mesenteric arteries were isolated and set up for isometric recording. Responses to electrical field stimulation (EFS) were obtained under basal and raised tone conditions induced by U46619, a thromboxane A2 mimetic. The nature of the neurotransmitters involved in the mediation of the electrically-evoked responses was assessed using an α1-adrenoceptor antagonist, prazosin and/or the P2X receptor desensitizing agent, α,β-methyleneATP, an α2-adrenoceptor RX811059 antagonist, and a neuropeptide Y Y1 receptor antagonist BIBP3226. In separate experiments, responses to nerve stimulation were investigated in rat mesenteric small arteries pressurized to 90 mmHg. The effects of a selective α1-adrenoceptor antagonist, YM-12617, and selective P2X1 receptor antagonist, NF-449, on the electrically-evoked response were determined. Under basal tone conditions the electrically-evoked contractile responses in porcine whole mesenteric bed and isolated arteries were exclusively mediated by noradrenaline (NA) since they were inhibited by prazosin. However, under conditions of raised tone, the electrically-evoked responses were enhanced and a role for ATP was evident since these responses were sensitive to α,β-methyleneATP. Responses to exogenous NA and α,β-methyleneATP were also enhanced at raised tone indicating a postjunctional mechanism of enhancement. Nifedipine attenuated the enhanced responses to EFS and α,β-methyleneATP suggesting a possible role for L-type calcium channels in the mediation of the enhanced responses. In rat pressurised mesenteric arteries the electrically-evoked vasocontractile responses were sensitive to YM-12617 and NF-449, indicating that NA and ATP were involved in the mediation of these responses. Raising tone with U46619 in these arteries enhanced the electrically-evoked contractile response; under these conditions responses were sensitive to both YM-12617 and NF-449. The present study supports the observation that ATP becomes a more important sympathetic neurotransmitter under conditions of raised tone in contrast to when tone is absent. In porcine mesenteric vascular preparations NA predominates as the main sympathetic neurotransmitter under conditions of basal tone. However, when tone was raised the responses were enhanced and a role for ATP became evident.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Normative Values of Peripapillary Retinal Nerve Fiber Layer Thickness in a Middle Eastern Population

Purpose. Peripapillary retinal nerve fiber layer (pRNFL) thickness is subject to high variability. Normative values of pRNFL thickness remain undocumented in the Middle East. The aim of our study is to assess the normative values of pRNFL thickness in a Middle Eastern population. Methods. A retrospective chart review of 74 patients was conducted. Outpatients who had presented to the ophthalmology clinic at the Jordan University Hospital between January 2016 and July 2018 were consecutively sampled. Measurements had been recorded using Fourier-domain optical coherence tomography. Multivariable regression models were developed to generate predicted normative values with adjustments to candidate confounders. Results. The mean global pRNFL thickness was 99 ± 11 μm. The mean quadrantic pRNFL thickness increased from the nasal quadrant (75 ± 16 μm) to the temporal (82 ± 20 μm), superior (114 ± 20 μm), and inferior (125 ± 20 μm) quadrants. Gender and eye sidedness did not contribute to the variability in pRNFL thickness. The relationship between aging and pRNFL thinning is independent of diabetes mellitus type 2 and systemic hypertension. Both systemic conditions significantly predicted pRNFL changes despite negative fundoscopic findings. Conclusions. Our set of predicted normative data may be used to interpret measurements of pRNFL thickness in Middle Eastern patients. Our findings suggest that systemic conditions with potential ocular manifestations may require consideration in predictive models of pRNFL thickness, even in the absence of gross fundoscopic findings. Normative data from additional Middle Eastern populations are required to appraise our models, which adjust for common clinical confounders

Morphometric analysis of the inferior vena cava and its clinical correlations using abdomino-pelvic computed tomography: Series from a Jordanian population

INTRODUCTION AND IMPORTANCE: This study aimed to determine the impact of DM, HTN and age on IVC dimensions as measured by CT scan relevant to guide interventions in a Jordanian population. PRESENTATION OF CASES: Two hundred patients were selected from those referred to the Radiology Department, Jordan University Hospital, Amman, Jordan for clinical evaluation. Patients were divided into three age subgroups. Age, sex, and comorbidities such as DM and HTN were identified and saved for later use. All dimensions of the IVC were measured using an abdomino-pelvic CT scanner. CLINICAL DISCUSSION: A full morphometric analysis of the IVC would provide a better understanding of the dynamicity of the IVC in relation to its blood flow. Our results revealed that the length of the IVC was significantly shorter with age (P = 0.003). DM significantly affected the length of the IVC (P = 0.044). Hypertension also significantly affected the length of the IVC (P = 0.031), but it did not significantly affect the anterio-posterior or the transverse diameters of the IVC. CONCLUSION: The length of the IVC was significantly shorter with age, DM and hypertension. Morphometric measures of the IVC are of great clinical importance as they may assist in medical or surgical intervention and follow-up

Use of magnetic resonance imaging to determine laterality of meniscal size in healthy volunteers.

INTRODUCTION:The menisci are responsible for several functions. They are shock absorbers during dynamic loading on the knee and provide a broader surface area on which to distribute stress evenly to the tibia and femur. These functions allow for smoother movement and greater stability of the knee joint. Meniscal injury can be a great impediment to the function of the knee. Therefore, in the case of meniscal injury, our main concern is the relief of patient symptoms, followed by consequent restoration of meniscal function to the greatest of our ability. To prevent the long terms effects of a meniscectomy, meniscal allograft transplantation (MAT) was developed. The potential of using the size of the contralateral healthy menisci, to determine the size of the menisci to be replaced, will be discussed. METHODS:Knee MRIs done on healthy patients in the past 5 years were reviewed. Magnetic Resonance Imaging was performed using a 3-T scanner. Each individual was examined with knee joints in full extension. Measurements were performed two separate times, two weeks apart. A mean of three measurements was made during each session to reduce error. Thirty-eight normal bilateral knee joints MRIs remained (16 males, 22 females). Participants were sampled from the institutional Picture Archiving and Communication System (PACS). Age, gender, and the medial meniscal and lateral meniscal size of both knees were recorded. The laterality of the menisci was compared between both knees in each patient. RESULTS:A total of 38 patients were included in this study, with a mean age of 37.39 (±9.50) years. They were 16 (42.1%) men and 22 (57.9%) women. We didn't find any significant difference in the mid-coronal section between left and right knees meniscal measurements. None of the measurements were significantly different between men and women. There was no significant difference in the medial mid-sagittal section or lateral mid-sagittal section between left and right knee meniscal measurements. CONCLUSION:The results obtained in this study may support the use of MRI of the bilateral knee to obtain an appropriately sized allograft