The Medial Triquetrohamate Portal: A New Portal in Wrist Arthroscopy. Anatomical Study.

Introduction Continuing advances in wrist arthroscopy and better understanding of carpal conditions have created the need to design new wrist access portals that facilitate the implementation of new surgical techniques. The aim of this study was to define and verify the safety of the medial triquetrohamate (MTH) portal. Description of the technique The MTH portal is located about 5-10 mm ulnar and 2-3 mm distal to the midcarpal ulnar portal, ulnar to the extensor digitorum communis (EDC) tendon of the fourth and fifth fingers, and radial to the extensor digiti quinti (minimi) (EDQ) tendon. Methods An anatomical study was performed on 15 upper limb specimens from 15 human cadavers. Iatrogenic injuries to potentially at-risk neurovascular and tendinous structures were assessed, and the distance from the portal to these structures was measured. Results There were no iatrogenic injuries to the structures at risk. Mean distances from the MTH portal to the EDC tendon of the fourth and fifth fingers and to the EDQ tendon were 4.67 ± 0.35 mm and 7.27 ± 0.18 mm, respectively. No differences were observed between the left and right wrists. The distance from the MTH portal to the dorsal sensory branch of the ulnar nerve was 15.07 ± 0.44 mm. The structure with the highest risk of injury was the EDC tendon of the fourth and fifth fingers, with a distance of less than 5 mm. Conclusions The MTH portal is safe, reproducible and facilitates the implementation of various techniques related to midcarpal pathology.

Influence of Physical Activity and Cup Orientation on Metal Ion Release and Oxidative Stress in Metal-on-Metal and Ceramic-on-Metal Total Hip Arthroplasty.

BACKGROUND: Metal-on-metal (M-M) total hip arthroplasty (THA) has shown adverse reactions to metal debris, abnormal soft-tissue reactions, and high blood metal ion levels. This study aims to: (1) assess whether the toxicity of high levels of ions is related to altered oxidative stress and (2) evaluate tribological factors related to increased blood levels of chromium (Cr) and cobalt (Co) ions. METHODS: A cross-sectional analytical descriptive study was conducted on 75 patients. A total of 25 underwent M-M THA, 25 ceramic-on-metal (C-M) THA, and 25 were on the THA waiting list. Ion metallic levels in blood, oxidative stress, physical activity, and implant position were compared. RESULTS: In the M-M group, Co and Cr levels were significantly higher than those found in the C-M group and the control group (p < 0.01). We found no differences in terms of oxidative stress between the groups. Also, we did not find a correlation between metal blood levels and oxidative stress indicators, the physical activity of the patients or the position of the implants between groups. CONCLUSIONS: The use of M-M bearing surfaces in THA raises the levels of metals in the blood without modifying oxidative stress regardless of the physical activity levels of the patients. Therefore, although patients with M-M bearings require close monitoring, it does not seem necessary to recommend the restriction of physical activity in patients with M-M or C-M arthroplasties.

Early-Stage Breast Cancer Detection in Breast Milk.

Breast cancer occurring during pregnancy (PrBC) and postpartum (PPBC) is usually diagnosed at more advanced stages compared with other breast cancer, worsening its prognosis. PPBC is particularly aggressive, with increased metastatic risk and mortality. Thus, effective screening methods to detect early PrBC and PPBC are needed. We report for the first time that cell-free tumor DNA (ctDNA) is present in breast milk (BM) collected from patients with breast cancer. Analysis of ctDNA from BM detects tumor variants in 87% of the cases by droplet digital PCR, while variants remain undetected in 92% of matched plasma samples. Retrospective next-generation sequencing analysis in BM ctDNA recapitulates tumor variants, with an overall clinical sensitivity of 71.4% and specificity of 100%. In two cases, ctDNA was detectable in BM collected 18 and 6 months prior to standard diagnosis. Our results open up the potential use of BM as a new source for liquid biopsy for PPBC detection. SIGNIFICANCE: For the first time, we show that BM obtained from patients with breast cancer carries ctDNA, surpassing plasma-based liquid biopsy for detection and molecular profiling of early-stage breast cancer, even prior to diagnosis by image. See related commentary by Cunningham and Turner, p. 2125. This article is featured in Selected Articles from This Issue, p. 2109.

[Impact of the COVID-19 pandemic and the strict population confinement on hip fracture incidence in Spain: A systematic review]. / Impacto de la pandemia por COVID-19 y el confinamiento estricto de la población en la incidencia de fractura de cadera en España. Una revisión sistemática.

BACKGROUND AND OBJECTIVE: During the COVID-19 pandemic, a strict population confinement was decreed in Spain. In a situation of health crisis and health system saturation, knowledge of pathologies whose treatment cannot be delayed is of great importance for the correct management of resources and processes. The objective was to determine the influence of the COVID-19 pandemic and the strict population confinement on hip fracture incidence in Spain. MATERIAL AND METHOD: Systematic review following the PRISMA guidelines. Search in Pubmed and Chocrane Library on 11/11/2022: hip fracture and COVID-19 and Spain. RESULTS: Six studies met the inclusion criteria, 50% showed a decrease in the hip fractures incidence during strict population confinement (all in Comunidad de Madrid hospitals), and in the other 50% there were no differences (all in other region hospitals). It was constant that hip fractures, either did not decrease, or decreased much less than the rest of fractures during the period of strict population confinement, increasing their relative number with respect to the total admissions in orthopedic surgery and traumatology. CONCLUSIONS: The behavior of the hip fractures number during the strict population confinement decreed by the COVID-19 pandemic has not been symmetrical in all regions. To design and implement contingency plans in the event of a pandemic situation, these data must be taken into account in order to properly plan material and human resources.

Feasibility and safety of targeted axillary dissection guided by intraoperative ultrasound after neoadjuvant treatment.

BACKGROUND: Axillary management in cN + axillary nodes after neoadjuvant systemic therapy (NST) in breast cancer (BC) remains under research with the aim of de-escalation of axillary node dissection (ALND). Several axillary guided localization techniques have been reported. This study evaluates the safety of intraoperative ultrasound (IOUS) guided targeted axillary dissection (TAD) in a large sample after the results of ILINA trial. MATERIALS: Prospective data have been collected from October 2015 to June 2022 in patients with cT0-T4 and positive axillary lymph nodes (cN1) treated with NST. Before NST, an ultrasound visible marker was placed into the positive node. After NST, IOUS guided TAD was performed including sentinel node biopsy (SLN). Until December 2019, all patients underwent an ALND after TAD procedure. From January 2020, ALND was spared in those patients with an axillary pathological complete response (pCR). RESULTS: 235 patients were included. pCR (ypT0/is ypN0) was achieved in 29% patients. Identification rate (IR) of the clipped node by IOUS was 96% (95% IC, 92.5-98.1%) and IR of SLN was 95% (95% IC, 90.8-97.2%). False negative rate (FNR) for TAD procedure (SLN + clipped node) was 7.0% (95% IC, 2.3-15.7%), which decreased to 4.9% when a total of 3 or more nodes were removed. Axillary ultrasound before surgery assessed residual disease with an AUC of 0.5241. Residual axillary disease tend to be the most significant factor for axillary recurrences. CONCLUSIONS: This study confirms the feasibility, safety and accuracy of IOUS guided surgery for axillary staging after NST in node positive BC patients.

All-Arthroscopic Triangular Fibrocartilage Complex Ligamentoplasty: Technique and Results.

Objective The aim of the study is to describe the modified all-arthroscopic technique for triangular fibrocartilage complex (TFCC) ligamentoplasty in chronic injuries of the TFCC with distal radioulnar joint (DRUJ) instability, and to present the results obtained. Methods A prospective study was conducted including 11 consecutive patients with chronic TFCC injury with DRUJ instability who underwent an all-arthroscopic TFCC ligamentoplasty. During follow-up, the range of joint motion, grip strength, pain according to the visual analog scale (VAS), functional outcomes according to the Mayo Wrist Score (MWS), and the QuickDASH Score were measured, and any complications and necessary reinterventions were recorded Results We analyzed 11 patients with distal radioulnar ligament injury treated using the all-arthroscopic ligamentoplasty technique. Mean follow-up was 31.5 ± 4.4 (range 12-58) months. The technique presented achieved DRUJ stability in 100% of cases at 12 months. Grip strength and pain, showed a statistically significant improvement between the preoperative score and the two postoperative assessments. Functional assessment using the QuickDASH score and the MWS also improved significantly. Conclusion The all-arthroscopic technique for the reconstruction of irreparable peripheral TFCC tears is a reliable technique, intended not only to minimize the surgical trauma to reduce postoperative pain and to facilitate rehabilitation, but also to improve both the quality of the reconstruction and the functional outcome.

Impact of strict population confinement on fracture incidence during the COVID-19 pandemic. Experience from a public Health Care Department in Spain.

BACKGROUND: the COVID-19 pandemic has led to drastic "stay-at-home" measures for the population. The aim of this study was to know the influence of the population strict confinement on the presentation of the different types of fracture as well as on the needs of hospital admission by the Orthopedic Surgery and Traumatology Service. METHODS: a retrospective observational analytical descriptive study was carried out on the population attended in the Emergency Services of two general hospitals in a public Health Care Department in Spain. Data were studied from the two-months confinement period in 2020 and compared with the same period in 2018 and 2019. RESULTS: A total of 56,332 emergency cases were included. There was a decrease in the total number of patients attended along the confinement period compared to the same period in the two previous years. Fracture cases decreased by 58,8% in the confinement period (330 in 2020; 715 in 2018 and 884 in 2019). Also there was a 37,6% reduction in fractures needing admission or surgery. The percentage distribution of the types of fractures that required admission resulted in a decrease in upper and lower limb fractures, whereas the number of vertebral and hip fractures remained unchanged. CONCLUSIONS: both the reduction of fractures attended in the emergency department and the maintenance of the number of hip fractures must be taken into account when establishing contingency plans in the event of a pandemic situation in order to properly plan human resources and materials.

The Volar Distal Radioulnar Portal in Wrist Arthroscopy: An Anatomical Study.

Background Advances in wrist arthroscopy and the emergence of novel surgical techniques have created a need for new portals to the wrist. The aim of this study was to define and verify the safety of the volar distal radioulnar (VDRU) portal. Description of the Technique The VDRU portal is located ∼5 to 10 mm proximal to the proximal wrist crease, just on the ulnar edge of flexor carpi ulnaris tendon and radial to the dorsal cutaneous branch of the ulnar nerve. The ulnar styloid marks the distal point of the portal. Methods An anatomical study was performed on 12 upper extremity specimens of 6 human cadavers. Iatrogenic injuries of neurovascular structures potentially at risk were assessed, and the distance from the portal to these structures was measured. Results No iatrogenic injuries of the structures at risk occurred. Mean distances from the VDRU portal to the ulnar neurovascular bundle, the radial branch of the dorsal sensory branches of the ulnar nerve (DSBUN), and the ulnar branch of the DSBUN were 9.29 ± 0.26 mm, 8.08 ± 0.25 mm, and 10.58 ± 0.23 mm, respectively. There were no differences between left and right wrists. The distances from the VDRU portal to the ulnar neurovascular bundle and the ulnar branch of the DSBUN were significantly shorter in women; this distance was not less than 7 mm in any case. Conclusions The VDRU portal is safe, reproducible, and facilitates the implementation of various techniques related to triangular fibrocartilage complex pathology.

Leveraging the increased rates of pathologic complete response after neoadjuvant treatment in breast cancer to de-escalate surgical treatments.

INTRODUCTION: Breast conservative surgery (BCS) and sentinel lymph node biopsy (SLNB) after neoadjuvant treatment (NAT) is safe and effective for selected patients. This aim of this study is to evaluate the impact of anatomic site of response on outcomes and to assess the real population who may benefit from nonsurgical approaches after NAT. MATERIAL AND METHODS: From a prospectively maintained database, patients with T1-4 N0-2 breast cancer undergoing NAT were identified. Clinicopathological and survival rates were compared in relation to response and anatomic site of response. RESULTS: Six hundred and forty-six patients were included in the study. Pathologic complete response (pCR) was an independent factor for BCS and SLN. HER2 positive and TN tumors with cN0 achieving a breast pCR remain ypN0 (p = .002). Residual axillary disease was associated with breast residual tumor (p = .05) and subtype (p = .001). With a median follow up of 35.25 months, patients with any pCR had improved survival when compared with partial response, but not significant differences between pCR, axillary pCR, or breast pCR. CONCLUSION: Achieving a pCR increases BCS and SLN. In selected subgroups, sparing any axillary surgery after NAT maybe feasible. In cN+ patients, any pCR was associated with survival, but not the anatomic site of response.

Arthroscopic Reinsertion of Acute Injuries of the Scapholunate Ligament Technique and Results.

Objective To describe a technique for treating acute injuries of the scapholunate ligament (SLL) by performing an arthroscopic reinsertion of the SLL and dorsal capsulodesis and to present the results obtained. Methods The study deals with an analytical, prospective clinical study that included 19 consecutive patients with acute injury of the SLL. The range of joint motion, grip strength, pain according to the visual analog scale, functional outcomes according to the Mayo Wrist Score (MWS), and the QuickDASH Score were studied preoperatively and 6 and 12 months postoperatively. The complications and necessary reinterventions were recorded. Results Nineteen patients with acute injury of the SLL were studied; mean age was 44 ± 2 years, 74% males, 58% complete rupture, and 42% partial rupture, treated with the above-mentioned technique. Thirty-seven percent also had a distal radius fracture and there was one case of perilunate dislocation. Improvement in pain, grip strength, joint balance, and functionality was observed 6 and 12 months postoperatively, with 79% of the cases with good or excellent results Conclusion The arthroscopic reinsertion and dorsal capsular reinforcement of the SLL, allow a reliable and stable primary repair of the dorsal aspect of the ligament in acute or subacute SL injuries where there is tissue that can potentially be repaired, thus achieving an anatomical repair similar to that obtained with open surgery, but without the complications and stiffness secondary to aggressive interventions on the soft tissues that are inherent to the open dorsal approach.

SOLTI-1503 PROMETEO TRIAL: combination of talimogene laherparepvec with atezolizumab in early breast cancer.

New treatment strategies such as immune checkpoint inhibitors and oncolytic viruses are opening new possibilities in cancer therapy. Preliminary results in melanoma and other tumors showed that the combination of talimogene laherparepvec with an anti-PD-1/PD-L1 or anti-CTLA4 has greater efficacy than either therapy alone, without additional safety concerns beyond those expected for each agent. The presence of residual cancer after neoadjuvant chemotherapy in early breast cancer patients is an unmet medical need. SOLTI-1503 PROMETEO is a window of opportunity trial, which evaluates the combination of talimogene laherparepvec in combination with atezolizumab in women with operable HER2-negative breast cancer who present residual disease after neoadjuvant chemotherapy. The primary end point is the rate of residual cancer burden 0/1. Clinical Trial Registration: NCT03802604.

Percutaneous ultrasound-guided vacuum-assisted excision of benign breast lesions: A learning curve to assess outcomes.

OBJECTIVE:: To evaluate the efficacy and learning curve of ultrasoundguided vacuum-assisted excision (US-VAE) of benign breast lesions, and to assess characteristics associated with residual lesion. METHODS:: This was a retrospective study with institutional review board-approval. Sonographic and clinical follow-up were performed 6 months after intervention. Effectiveness and safety of the technique were analyzed. The cumulative summation (CUSUM) graphs were used to evaluate learning curves concerning complete excision and hematoma. RESULTS:: 152 ultrasound-VAEs in 143 patients were included. Initial complete resection was achieved in 90.8 % (138 of 152). 6-month follow-up was completed for 143 (94%) of cases and complete resection was observed in 72 % (100 of 143). Mean maximum size without residual tumor was 16.9 mm, while with residual lesion it was 21.9 mm (p = < 0.001), with a volume of 1.53 and 3.39 cm3, respectively (p = < 0.001). Increase in lesion size and volume was associated with less effectiveness (p = 0.05), clinical control (p = 0.05), and higher risk of clinically significant hematoma (p = 0.05). Receiver operating characteristic analysis demonstrate a volume threshold of 2.6 cm3 (r = 0.71, specificity 84.5%) for leaving no residual lesion. Cumulative summation graphs demonstrate that, on average, 11 excisions were required to acquire skills to perform complete excision in more than 80% at the end of the ultrasound-VAE and 18 excisions at 6 months. CONCLUSION:: Ultrasound-VAE is an effective treatment for benign breast lesions. Breast lesion volume should be considered when assessing for percutaneous treatment. ADVANCES IN KNOWLEDGE:: A follow-up of the learning process of ultrasound-VAE will be a valuable tool to assess the efectiveness and safety of the technique i.

Arthroscopic Scapholunate Capsuloligamentous Repair: Suture With Dorsal Capsular Reinforcement for Scapholunate Ligament Lesion.

Scapholunate ligament (SLL) injury is the most frequent injury of the intrinsic carpal ligaments. The dorsal part of the SLL is the most important part for the stability of the scapholunate joint, and tears of this part and at least one of its secondary capsular attachments cause scapholunate dissociation. The arthroscopic technique most frequently used for acute injuries is reduction and fixation with Kirschner wires, and techniques that involve a primary repair of the injured ligament are performed by open surgery with efficient results. However, they lead to significant stiffness of the wrist due to injury to the soft tissue caused by damage to the secondary dorsal stabilizers; the dorsal blood supply; and in many cases, the proprioceptive innervation of the posterior interosseous nerve. We present an all-arthroscopic technique for the direct repair of acute injuries of the dorsal part of the SLL using bone anchors, complemented by a dorsal arthroscopic plication that reconstructs the dorsal capsulo-scapholunate septum of the scapholunate complex.

Laparoscopic Management of Ureteral Endometriosis and Hydronephrosis Associated With Endometriosis.

STUDY OBJECTIVE: To evaluate if laparoscopic treatment of ureteral endometriosis is feasible, safe, and effective and to determine if ureteral dilatation and/or the number of incisions increases complications. DESIGN: An institutional review board-approved retrospective cohort study of consecutive patients who underwent surgery for deep infiltrating endometriosis involving the ureter with hydronephrosis (Canadian Task Force classification III). SETTING: A university hospital. PATIENTS: Of 658 patients who had surgery for deep infiltrating endometriosis between November 2004 and December 2013, 198 of the 658 patients had ureteral endometriosis and required ureterolysis, and 28 of the 198 patients were identified with ureteral dilatation and hydronephrosis associated with endometriosis. INTERVENTIONS: Of these 28 cases, 15 ureterolyses, 12 reanastomoses, and 1 reimplantation were performed. MEASUREMENTS AND MAIN RESULTS: Medical, operative, and pathological data on the evolution of pain, urinary complaints, fertility, complications, and recurrences were collected from clinical records. Additionally, telephone interviews were performed for the follow-up of long-term outcomes. All 28 patients had concomitant surgical procedures because of endometriosis elsewhere in the pelvis or abdomen; 12 (42.9%) underwent surgery of the bowel, whereas 5 (17.9%) had bladder surgery. The evolution of pain after surgery showed a positive response (mean dysmenorrhea evaluation measured by the Numeric Pain Rating Scale from 0-10 preoperatively at the short-term follow-up and the long-term follow-up: 7.25-1.73 and 0.25, respectively). Three complications were noted in the group of 28 patients with ureterohydronephrosis; 1 required surgical reintervention. Logistic regression analyses found vaginal incision (odds ratio = 2.08; 95% CI 0.92-4.73), bladder incision (odds ratio = 8.77; 95% CI 3.25-23.63), number of incisions (odds ratio = 2.12; 95% CI 1.29-3.47), and number of previous surgeries (odds ratio = 1.26; 95% CI 0.93-1.71) as independent risk factors for complications in the group of 198 patients. Three patients underwent reoperation in the group of 28 patients: 1 for ureterovaginal fistula, 1 for persistent ureter dilatation and hydronephrosis, and 1 for persistent pain. CONCLUSION: Laparoscopically assisted ureterolyses, ureteral reanastomoses, and ureteral reimplantation are feasible, safe, and effective treatments for ureteral endometriosis. Complete laparoscopic excision is possible with minimal complications, which seem to be associated with the number of incisions. Ureteral endometriosis should be suspected in all cases of deep infiltrating endometriosis.

Intraoperative Ultrasound-Guided Lumpectomy Versus Mammographic Wire Localization for Breast Cancer Patients After Neoadjuvant Treatment.

BACKGROUND: Intraoperative ultrasound (IOUS)-guided lumpectomy in early breast cancer has shown advantages over other techniques. However, the use of IOUS has been less explored after neoadjuvant treatment (NAT). This study aimed to compare IOUS- and wire localization (WL)-guided surgery in breast cancer patients after NAT. METHODS: The study enrolled patients treated with NAT who underwent breast-conserving surgery (BCS) between July 2008 and December 2012. For the patients with a hydrogel marker or residual tumor visible on ultrasound, an IOUS-guided surgery was performed (IOUS group). The patients with a standard marker or hydrogel marker not visible on ultrasound underwent a WL-guided surgery (WL group). RESULTS: The study investigated 214 patients: 145 (67.8 %) in the IOUS group and 69 (32.2 %) in the WL group. The patient and tumor characteristics were comparable between the two groups. For the patients who had a pathologic complete response (pCR) or microscopic disease, the volume excised was lower in the IOUS group (p = 0.03). The rate of reexcision for positive or close margins was similar in the two groups (p = 0.80). After a median follow-up period of 43 months, the local recurrence rates did not differ significantly between the two groups. CONCLUSIONS: Compared with WL surgery, IOUS seems to lower the volume of resection in patients with pCR or minimal microscopic disease after NAT without compromising margins and local recurrences. BCS can easily be achieved with IOUS for patients with a good response after NAT.

Orthopedic versus surgical treatment of Gartland type II supracondylar humerus fracture in children.

The choice of orthopedic or surgical treatment for Gartland type II supracondylar humeral fractures remains controversial. The aim of this study was to retrospectively compare the outcomes in orthopedic and surgical treatment in type II supracondylar humeral fractures in children treated in the Orthopedic and Traumatology Children Unit of our tertiary hospital over the period between 2007 and 2010. This study suggests that orthopedic treatment is a valid option for the treatment of this type of fractures, with radiological and functional results as good as those obtained with surgical treatment, avoiding surgical complications and decreasing the hospital stay.

Diabetes impairs the atrial natriuretic peptide relaxant action mediated by potassium channels and prostacyclin in the rabbit renal artery.

Diabetes is associated with increased prevalence of hypertension, cardiovascular and renal disease. Atrial natriuretic peptide (ANP) plays an important role in cardiovascular pathophysiology and is claimed to have cardioprotective and renoprotective effect in diabetic patients. The working hypothesis was that alloxan-induced diabetes might modify the vascular effects of ANP in isolated rabbit renal arteries and the mechanisms involved in such actions. Plasma ANP levels were higher in diabetic rabbits than in control rabbits. ANP (10(-12)-10(-7)M) induced a relaxation of precontracted renal arteries, which was lower in diabetic than in control rabbits. In arteries from both groups of animals, endothelium removal decreased the ANP-induced relaxation but inhibition of NO-synthesis did not modify ANP-induced relaxations. In KCl-depolarised arteries, relaxation to ANP was almost abolished both in control and diabetic rabbits. Tetraethylammonium (TEA) partly inhibited the relaxation to ANP in control rabbits but did not modify it in diabetic rabbits. Glibenclamide and 4-aminopyridine inhibited the relaxation to ANP, and these inhibitions were lower in diabetic than in control rabbits. Indomethacin potentiated the relaxation to ANP, more in control than in diabetic rabbits. In the presence of ANP the renal artery released thromboxane A(2) and prostacyclin, and the release of prostacyclin resulted decreased in diabetic rabbits. The present results suggest that diabetes produces hyporeactivity of the rabbit renal artery to ANP by mechanisms that at least include the reduced modulation by prostacyclin and a lower participation of ATP-sensitive K(+) channel (K(ATP)), voltage-sensitive K(+) channels (K(V)) and TEA-sensitive K(+) channels (K(Ca)).

Mechanisms underlying the diabetes-induced hyporeactivity of the rabbit carotid artery to atrial natriuretic peptide.

Atrial natriuretic peptide (ANP) plays an important role in the pathophysiology of the vascular complications in diabetes. The working hypothesis was that diabetes might modify the vascular actions of ANP in isolated rabbit carotid arteries and the mechanisms involved in these actions. ANP (10(-12)-10(-7)M) induced a relaxation of precontracted carotid arteries, which was lower in diabetic than in control rabbits. In arteries from both groups of animals, endothelium removal increased the ANP-induced relaxation. Isatin inhibited the relaxation to ANP both in arteries with and without endothelium. Carotid arteries from diabetic rabbits showed a decreased natriuretic peptide receptor (NPR)-A expression and an enhanced NPR-C expression. Inhibition of NO-synthesis did not modify ANP-induced relaxation in control rabbits but inhibited it in diabetic rabbits. In arteries with endothelium indomethacin enhanced the relaxation to ANP in control rabbits but did not modify it in diabetic rabbits. In endothelium-denuded arteries indomethacin inhibited the relaxation to ANP in both groups of animals. In KCl-depolarised arteries, relaxation to ANP was almost abolished both in control and diabetic rabbits. Tetraethylammonium inhibited the relaxation to ANP, and this inhibition was higher in diabetic than in control rabbits. These results suggest that diabetes produces hyporeactivity of the rabbit carotid artery to ANP by a mechanism that at least includes a reduced expression of NPR-A, an enhanced expression of NPR-C and a reduced participation of K(+)-channels. Furthermore, diabetes enhances endothelial NO release and diminishes the ratio thromboxane A(2)/prostacyclin. This increase of vasodilators could result from compensatory mechanisms counteracting the arterial hyporeactivity to ANP.