Oculomotor, vestibular, reaction time, and cognitive tests as objective measures of neural deficits in patients post COVID-19 infection.

Objective: An alarming proportion (>30%) of patients affected by SARS-CoV-2 (COVID-19) continue to experience neurological symptoms, including headache, dizziness, smell and/or taste abnormalities, and impaired consciousness (brain fog), after recovery from the acute infection. These symptoms are self-reported and vary from patient to patient, making it difficult to accurately diagnose and initiate a proper treatment course. Objective measures to identify and quantify neural deficits underlying the symptom profiles are lacking. This study tested the hypothesis that oculomotor, vestibular, reaction time, and cognitive (OVRT-C) testing using eye-tracking can objectively identify and measure functional neural deficits post COVID-19 infection. Methods: Subjects diagnosed with COVID-19 (n = 77) were tested post-infection with a battery of 20 OVRT-C tests delivered on a portable eye-tracking device (Neurolign Dx100). Data from 14 tests were compared to previously collected normative data from subjects with similar demographics. Post-COVID subjects were also administered the Neurobehavioral Symptom Inventory (NSI) for symptom evaluation. Results: A significant percentage of post COVID-19 patients (up to 86%) scored outside the norms in 12 out of 14 tests, with smooth pursuit and optokinetic responses being most severely affected. A multivariate model constructed using stepwise logistic regression identified 6 metrics as significant indicators of post-COVID patients. The area under the receiver operating characteristic curve (AUC) was 0.89, the estimated specificity was 98% (with cutoff value of 0.5) and the sensitivity was 88%. There were moderate but significant correlations between NSI domain key variables and OVRT-C tests. Conclusions: This study demonstrates the feasibility of OVRT-C testing to provide objective measures of neural deficits in people recovering from COVID-19 infection. Such testing may serve as an efficient tool for identifying hidden neurological deficits post COVID-19, screening patients at risk of developing long COVID, and may help guide rehabilitation and treatment strategies.

Regulation of bladder muscarinic receptor subtypes by experimental pathologies.

1 The M3 muscarinic receptor subtype is widely accepted as the receptor on smooth muscle cells that mediates cholinergic contraction of the normal urinary bladder and other smooth muscle tissues, however, we have found that the M2 receptor participates in contraction under certain abnormal conditions. The aim of this study was to determine the effects of various experimental pathologies on the muscarinic receptor subtype mediating urinary bladder contraction. 2 Experimental pathologies resulting in bladder hypertrophy (denervation and outlet obstruction) result in an up-regulation of bladder M2 receptors and a change in the receptor subtype mediating contraction from M3 towards M2. Preventing the denervation-induced bladder hypertrophy by urinary diversion prevents this shift in contractile phenotype indicating that hypertrophy is responsible as opposed to denervation per se. 3 The hypertrophy-induced increase in M2 receptor density and contractile response is accompanied by an increase in the tissue concentrations of mRNA coding for the M2 receptor subtype, however, M3 receptor protein density does not correlate with changes in M3 receptor tissue mRNA concentrations across different experimental pathologies. 4 This shift in contractile phenotype from M3 towards M2 subtype is also observed in aged male Sprague-Dawley rats but not females or either sex of the Fisher344 strain of rats. 5 Four repeated, sequential agonist concentration response curves also cause this shift in contractile phenotype in normal rat bladder strips in vitro, as evidenced by a decrease in the affinity of the M3 selective antagonist p-fluoro-hexahydro-sila-diphenidol (p-F-HHSiD). 6 A similar decrease in the contractile affinity of M3 selective antagonists (darifenacin and p-F-HHSiD) is also observed in bladder specimens from patients with neurogenic bladder as well as certain organ transplant donors. 7 It is concluded that although the M3 receptor subtype predominantly mediates contraction under normal circumstances, the M2 receptor subtype can take over a contractile role when the M3 subtype becomes inactivated by, for example, repeated agonist exposures or bladder hypertrophy. This finding has substantial implications for the clinical treatment of abnormal bladder contractions.

Cyclophosphamide cardiotoxicity in bone marrow transplantation: a prospective evaluation of new dosing regimens.

Cyclophosphamide (CY) cardiotoxicity may be a lethal complication of bone marrow transplantation. Previous echocardiographic studies have reported that left ventricular dysfunction due to CY occurs in over 50% of patients undergoing transplantation. To evaluate the cardiotoxicity of new dosing protocols that included twice-daily rather than once-daily CY, 44 bone marrow transplantation patients were prospectively evaluated with serial ECGs and echocardiograms. Twenty-six patients received a once-daily lower-dose protocol (mean total 87 +/- 11 mg/kg), and 18 patients received a twice-daily higher-dose (mean total 174 +/- 34 mg/kg) CY regimen. In the higher-dose CY group, significant reductions in summed ECG voltage (-20%) (P less than .01) and increases in left ventricular mass index (LVMI) (+10%) (P less than .05) were detected in the first week following therapy. These changes resolved by the third week following CY and were significantly greater than the changes noted in the lower-dose group. However, left ventricular ejection fraction (EF) did not change significantly in either group. Five patients developed clinical cardiotoxicity (four, pericarditis; one, congestive heart failure); four of the five patients were in the higher-dose group (P = .14). Only a prior history of congestive heart failure or a baseline EF less than 50% was an independent correlate of clinical cardiotoxicity (P less than .05). Thus, dose-dependent cardiotoxicity following the use of CY for bone marrow transplantation is evident as reversible decreases in ECG voltage and increases in left ventricular mass, possibly reflecting myocardial edema or hemorrhage. However, systolic dysfunction is much less common with these new twice-daily dosing regimens when compared with earlier studies of high-dose once-daily CY.

Bile duct ligation induced acute inflammation up-regulates cyclooxygenase-2 content and PGE2 release in guinea pig gallbladder smooth muscle cell cultures.

INTRODUCTION: This study examines hypotheses that BDL induces increased guinea pig gallbladder smooth muscle PGE2 release by up-regulation of COX-2. METHODS: BDL, Sham and Control Hartley guinea pig gallbladders were placed in cell culture, grown to confluence and underwent Western Blot analysis for smooth muscle cell content of COX-1, COX-2, Prostacylin Synthase, actin, caldesmon, vinculin, meta-vinculin and tropomyosin and were assayed for basal release of 6-keto-PGF(1alpha), PGE2 and TxB2 by EIA. RESULTS: BDL did not alter content of smooth muscle cytoskeletal proteins. BDL for 48 h increased smooth muscle cell release of PGE2 and 6-keto-PGF(1alpha) by 3-fold or more when compared to the Control and Sham groups. Western Blot analysis showed increased content of COX-2 in the BDL group. CONCLUSIONS: BDL for 48 h markedly increased endogenous guinea pig smooth muscle cell PG release, which was due to increased COX-2 synthesis.

The effect of single intravenous doses of cimetidine or ranitidine on gastric secretion.

Intravenous cimetidine, 300 mg or 400 mg, or ranitidine, 50 mg, was administered as a single dose to 36 volunteers in a randomized, crossover fashion. Aspirates of gastric juice were obtained after dosing, and the pH, titratable acidity, gastric fluid volume, and gastric acid output were determined from baseline through 71/2 hours for each subject. Each intervention significantly increased pH and suppressed hydrogen ion concentration, gastric fluid volume, and gastric acid output. Both the magnitudes of the changes when compared with baseline and the time of the mean maximum effects were similar in all three drug regimens. The effect of all three interventions on gastric fluid volume and gastric acid output diminished sharply after 6 hours. The data indicate that the gastric secretory response to all three interventions did not differ substantially.

Response of colo-rectal hepatic metastases to concomitant radiotherapy and intravenous infusion 5 fluorouracil.

Twenty-three patients with colo-rectal hepatic metastases were retrospectively reviewed after completing treatment with split course liver irradiation and continually infused concomitant intravenous 5-fluorouracil. Although no patient attained a complete response, an objective partial response was documented in 15 (Responders). The Responders had a median survival of 45 weeks whereas Non-responders had a median survival of 17 weeks. Patients with metastatic disease solely in the liver or those with a Karnofsky performance score (k.p.s) of over sixty, had a median survival of 49 weeks. Patients with multiple organ metastatic involvement had a median survival of 25 weeks and those with a Karnofsky with less than 60 had a median survival of 27 weeks. (p values of 0.006 and 0.03, respectively.) The overall survival of the group completing treatment was 30 weeks, and 19 patients (83%) achieved subjective palliation. The patients tolerated therapy well. There was minimal hematological toxicity; 3 patients developed a leucocyte count of less than 2000 and 1 developed a platelet count of 30,000. The palliation and prolongation of survival attained with minimal complications suggest that adjuvant liver irradiation with concomitant infusion 5-fluorouracil radiosensitization may be an option to offer patients identified to be at high risk of developing subclinical liver disease.

Doppler echocardiographic estimation of mitral valve area during changing hemodynamic conditions.

Patients with mitral stenosis often present during periods of hemodynamic stress such as pregnancy or infections. The Doppler pressure half-time method of mitral valve area (MVA) determination is dependent on the net atrioventricular compliance as well as the peak transmitral gradient. The continuity equation method of MVA determination is based on conservation of mass and may be less sensitive to changes in the hemodynamic state. To test this hypothesis, 17 patients admitted for catheterization with symptomatic mitral stenosis and no more than mild regurgitation underwent Doppler echocardiography at rest and during supine bicycle exercise targeted to an increase in heart rate by 20 to 30 beats/minute. Net atrioventricular compliance was also estimated noninvasively. Cardiac output and transmitral gradient increased significantly during exercise (p less than 0.001), while net atrioventricular compliance decreased (p less than 0.001). MVA by the pressure half-time method increased significantly during exercise from 1.0 +/- 0.2 to 1.4 +/- 0.4 cm2 (p less than 0.001). There was no significant difference in MVA estimation using the continuity equation comparing rest to exercise, with the mean area remaining constant at 0.8 +/- 0.3 cm2 (p = 0.83). Thus, during conditions of changing hemodynamics, the continuity equation method for estimating MVA may be preferable to the pressure half-time method.

Determining the optimal dosage regimen for H2-receptor antagonist therapy--a dose validation approach.

A large number of clinical studies have been performed to establish the safety and efficacy of H2-receptor antagonist therapy. Few if any of these studies have attempted to address the rationale for the dosage and/or dosage regimens being studied. This study is the first large-scale clinical trial, the purpose of which is to validate the chosen regimen and to address the issue of an optimal therapy for a specific patient population. A regimen of a single nightly dosage is generally acknowledged to offer the potential for improved patient compliance. Furthermore, recent research had suggested that suppression of nocturnal acid secretion is all that is required to heal duodenal ulcers. Hence such a regimen offered the potential for an effective lowered dosage of cimetidine with minimal interference with gastric physiology, increased safety and substantial efficacy. This multicentre, double-blind, placebo-controlled trial therefore evaluated a 4-week course of single night-time dosage of cimetidine. After 4 weeks of treatment the cumulative, endoscopically proven, ulcer healing rate with an 800 mg regimen was 73%, which was statistically higher and significantly superior to the 41% healing seen with placebo (P less than 0.001). The 400 mg nocte dosage regimen of cimetidine normally used as maintenance therapy was significantly inferior to the 800 mg nocte regimen (P = 0.01), and increasing the dosage to 1600 mg nocte for 4 weeks failed to provide a significant improvement in healing over the 800 mg nocte regimen. This 800 mg nocte regimen provided rapid pain relief, with 75% of the patients being free of night-time pain and 65% free of day-time pain, by the end of the first week. The 400 mg 'maintenance dosage' was unable to provide this degree of rapid, complete and early relief to patients with a duodenal ulcer. Furthermore, increasing the dosage to 1600 mg nocte failed to increase the level of early pain relief significantly, perhaps because the extensive response of duodenal ulcer patients to the 800 mg nocte regimen leaves little room for improvement. Based both on the early symptom relief and the ulcer healing rate during 4 weeks of treatment, it is concluded that an 800 mg night-time dosage of cimetidine may be an optimal regimen for many duodenal ulcer patients, particularly those who in the physician's opinion will benefit from a once-daily regimen.

High-output congestive heart failure following transjugular intrahepatic portal-systemic shunting.

A hyperdynamic circulatory state with elevated cardiac output, decreased peripheral vascular resistance, and sodium retention occurs in patients with portal cirrhosis. Surgical portal-systemic shunts and transjugular intrahepatic portal-systemic shunts (TIPS) have been shown to worsen the high-output state in these patients. However, clinical evidence of high-output congestive heart failure has been reported only rarely to complicate cirrhosis. We describe a patient who developed high-output congestive heart failure with markedly elevated filling pressures after TIPS and had complete resolution of heart failure after liver transplantation.

Massive hemothorax due to intrathoracic extramedullary hematopoiesis in a patient with thalassemia intermedia.

We report the case of a 49-year-old woman with thalassemia intermedia who developed a massive hemothorax due to hemorrhage from a large intrathoracic, paraspinal hematopoietic mass. Thoracotomy was required for initial control of bleeding. Postoperatively she received a total of 1,500 rads to the mass and has not had recurrence of the hemothorax. This complication of extramedullary hematopoiesis has not been previously reported, to our knowledge.

Transesophageal echocardiographic and clinical features of aortic intramural hematoma.

OBJECTIVE: This study sought to determine the transesophageal echocardiographic features and natural history of patients with aortic intramural hematoma. METHODS: The transesophageal echocardiograms of all patients who had symptoms indicative of aortic dissection over 6 years were reviewed. Measurements were made of the involved aortic segment in the study patients, and follow-up was obtained. RESULTS: In patients with aortic intramural hematoma, the wall thickness of the involved segment was significantly greater for descending segments than ascending segments (ascending aorta 7 +/- 2 mm, descending aorta 15 +/- 6 mm, p = 0.0016). In each case, the crescent-shaped intramural hematoma involved one wall predominantly, leading to compression of the aortic lumen. The findings of echolucent areas and displaced intimal calcium were found in the majority of patients. Four of eight patients with intramural hematoma of the ascending aorta were treated medically and four were treated surgically. The 30-day mortality was 50% in the medically treated patients and 0% in the surgically treated group. Four of 11 patients with isolated intramural hematoma of the descending aorta were treated medically and seven were treated surgically. All medically treated and 86% of surgically treated patients were alive at 30 days. CONCLUSIONS: Aortic intramural hematoma has distinct and identifiable transesophageal echocardiographic features. These data support those of previous studies documenting high morbidity and mortality in patients with aortic intramural hematoma.

Multimodal therapy for locally advanced breast cancer.

Thirty-one women with stage III breast cancer were prospectively treated with two cycles of cyclophosphamide (Cytoxan), doxorubicin hydrochloride (Adriamycin), fluorouracil, and tamoxifen citrate followed by a simple mastectomy with level I axillary dissection. Postoperatively, four additional cycles of the combination chemotherapy alternating with three cycles of 1500 rad (15 Gy) to the chest wall and lymphatics were given. Seventy-seven percent of patients had a greater than 50% reduction in tumor size after the initial chemotherapy. No tumor size progressed during therapy, and a single patient remained inoperable. Pathologic findings revealed nine patients with only microscopic residual tumor. Nuclear vacuolization was present in 42.8% of tumor cells after chemotherapy vs 14.2% of cells before chemotherapy. The mean follow-up for the groups is 24.3 months. To date, nine patients have had recurrence with only one isolated local recurrence. This therapy is effective in reducing primary tumor size and allows a limited mastectomy to be done with minimal morbidity.

Dose validation and study design criteria in current cimetidine studies.

A large dose validation study compared cimetidine 800 mg at bedtime, a dose known to provide maximum acid suppression through the night, with placebo, cimetidine 400 mg, and 1,600 mg in the treatment of acute duodenal ulcer. The study was also designed to assess the effects of smoking and ulcer size on duodenal ulcer healing. Results of the study indicated that both smoking and ulcer size negatively correlated with ulcer healing. Cimetidine 800 mg (75%) was superior to placebo (45%) and cimetidine 400 mg (60%) (P less than 0.05) in terms of ulcer healing. There was no statistically significant difference between cimetidine 800 mg and 1,600 mg (81%). Up to 80% of the patients treated with cimetidine 800 mg had some degree of pain relief after the first dose. Cimetidine 800 mg was superior to placebo with respect to both daytime and nighttime pain relief at all assessment points and was superior to 400 mg during the first week. There was no difference in pain relief between 800 mg and 1,600 mg at any assessment period. It was clear that cimetidine 800 mg is the most appropriate dosage in the acute therapy of duodenal ulcer, combining optimal healing with maximum pain relief.

Survey results on the current practice of ovum donation. Ovum Donor Task Force of the Psychological Special Interests Group of the American Fertility Society.

OBJECTIVE: To investigate how many programs currently have an ovum donor program and to examine the current state of the art in ovum donor programs regarding management, screening, and implementation. DESIGN: Surveys were sent to members of the Society for Assisted Reproductive Technology (SART) and the Psychological Special Interest Group of the American Fertility Society. RESULTS: Of 160 SART members, 82 surveys were returned. Psychological Special Interest Group surveys were excluded. A trend toward more third party reproduction was seen. There was little uniformity among programs regarding medical or psychological screening. Differences were seen between the screening and administration of ovum and sperm donation. CONCLUSIONS: Unlike sperm donation, ovum donation has begun in the known donor realm. Medical and psychological screening is currently limited in many ovum donor programs and highly variable with both known and anonymous donors. Most programs do use a mental health person as part of the screening process. More guidelines are needed to provide uniformity for the current practice of ovum donation.

Factors related to preferences in gamete donor sources.

OBJECTIVE: To survey fertile and infertile individuals concerning attitudes about donor insemination and ovum donation and to analyze whether gender, experience with infertility, and religion influences: [1] preference for choosing gamete donor over adoption or child-free living; [2] choice of selecting a known or anonymous donor; or [3] choice of disclosure or nondisclosure to any offspring. DESIGN: Patients in an infertility clinic and obstetrics and gynecology practice were asked to complete surveys. PARTICIPANTS: Three hundred nineteen individuals who completed surveys. MAIN OUTCOME MEASURES: A 14-item questionnaire (created for this study) with a demographic information section. RESULTS: No gender differences were observed for preference to use donor gametes, to adopt, or to live child free within the infertility group. In the obstetrics and gynecology group, men preferred adoption more than women and were less likely to use a donor. Choice of whether to use a donor, which donor source, and whether to disclose the use of a donor was influenced by gender, experience with infertility, and religion. CONCLUSIONS: Gender, experience with infertility, and religion influence an individual's choice in family building options as well as what information will be shared with the child. There is a wider acceptance of using known donor sources than has heretofore been seen and these options should be explored.

Gestational carrier pregnancy.

OBJECTIVE: To evaluate the results of a gestational carrier program in terms of pregnancy rates in fresh and cryopreserved cycles. DESIGN: Retrospective analysis. SETTING: Private IVF program. PATIENT(S): Women with uterine or medical reasons for unsuccessful gestation. INTERVENTION(S): In vitro fertilization of oocytes with fresh or cryopreserved ET to gestational carriers. MAIN OUTCOME MEASURE(S): Pregnancy rates and deliveries. RESULT(S): A PR of 56.3% and a cycle rate of 30.8% was achieved in each patient <40 years of age in 117 cycles of fresh or cryopreserved ET. There were no pregnancies for nine patients >40 years of age in 27 cycles. CONCLUSION(S): Carrier gestation offers a satisfactory solution to childlessness caused by uterine or major medical factors.

Characteristics and attitudes of parents of children born with the use of assisted reproductive technology.

OBJECTIVE: To explore the medical issues, attitudes, concerns, and choices that parents have about their children born with the use of assisted reproductive technology (ART). DESIGN: Retrospective and prospective survey. SETTING: An academic medical center and a private practice. PATIENT(S): Participants who conceived and were delivered of infants in two ART programs. INTERVENTION(S): A total of 373 patients were mailed an anonymous survey, a consent form, and the Parent Child Relationship Inventory. The rate of response was approximately 49% for clinic A and 33% for clinic B. MAIN OUTCOME MEASURE(S): Pregnancy outcomes and attitudes about parenting. RESULT(S): Respondents' major concerns during pregnancy revolved around miscarriage and the infant's health; complications occurred in 38.9% of first pregnancies. Parents believed that their children were more appreciated, that their children were not emotionally different, that ART did not create ongoing medical or emotional problems, and they were not overprotective as parents. Gender differences were statistically significant on attitudinal variables. CONCLUSION(S): Parents had concerns about pregnancy. Overall, men and women felt positive about ART and their parenting. The ART experience is associated with complex choices, attitudes, and emotions.

The role of transthoracic echocardiography in the management of patients seen in an outpatient cardiology clinic.

Transthoracic two-dimensional (2D) Doppler echocardiography may provide new or additional information in patients, but it is often not known whether the results alter the treatment plan. We investigated whether results of clinically indicated 2D echocardiography were different from the physician's clinical examination or led to changes in management in 200 consecutive outpatients seen in a university-based clinic. A questionnaire was completed by the physician regarding physical findings and treatment plan before 2D echocardiography was performed. After results were known, the physician was asked to report any differences compared with clinical examination or changes in patient management. Most patients (83%) were studied to evaluate left ventricular (LV) or valvular function. 2D echocardiography confirmed clinical assessment in 182 patients (one inadequate 2D echocardiogram) and disclosed a new diagnosis in 17. 2D echocardiography provided additional information, not expected from clinical assessment or history, in 94 patients. Clinical assessment, compared with 2D echocardiography, was concordant in 154 (77%) of 199 patients with regard to LV systolic function but in only 22 (50%) of 44 with valve disease. Alterations in management based on results of 2D echocardiography were instituted in 73 patients (36%), most often manifested by changes in pharmacologic therapy (n = 45; 62%). Results of 2D echocardiography obviated the need for further cardiac evaluation, surgery, or procedures in 30 patients, avoiding additional patient charges of $125,754.00. In contrast, results of 2D echocardiography led to the need for further evaluation, surgery, or procedures in 32 patients, resulting in additional patient charges of $70,860.00. In conclusion, 2D echocardiography provides new or additional information that results in changes in management strategy in one third of patients, and 2D echocardiography offers relative cost savings by avoiding additional procedures.

Immune function, mitogenicity, and angiogenic growth factor concentrations in lean and obese rodent sera: implications in obesity-related prostate tumor biology.

Some studies suggest that several tumors have a greater incidence in those patients with a high fat diet, such as colon, breast, and prostate. However, we wanted to determine the effects of obesity alone, independent of diet, on the progression of prostate tumor growth. Using a genetic model of obese and lean Zucker rats, we wanted to demonstrate any sera differences in the concentration of basic fibroblast growth factor (FGF-2) and vascular endothelial cell growth factor (VEGF), two important factors involved in the growth and progression of prostate cancer. We also wanted to investigate if there were any differences in immune function between the two sera, which could also account for uninhibited tumor growth, as well as differences in mitogenic stimulation. Female Zucker rat obese and lean sera were analyzed using ELISA assays for FGF-2, VEGF, and macrophage inflammatory protein-1 alpha (MIP-1a), as a measure of macrophage function. In addition, the sera of lean and obese sera were plated on wells growing LNCaP prostate cancer cells to determine differences in mitogenicity. We found a greater concentration of FGF-2 in the sera from obese Zucker rats compared to lean Zucker rats: 6.32+/-0.56 vs 3.48+/-0.34 pg/ml, respectively, P<0.05). We also demonstrated a greater concentration of VEGF in obese rat sera compared to lean sera: 54.4+/-4.1 vs 38.0+/-2.9 pg/mL, respectively, P<0.05). We detected a trend in mitogenic stimulation among LNCaP cells along the higher concentrations of the dose-response curve (0.72+/-0.06 vs 0.51+/-0.5). However, this was not statistically significant. In addition, we did not find a significant difference in MIP-1a macrophage activity levels between sera. To conclude, we speculate that the greater concentrations of VEGF and FGF-2 in the sera of obese rodents vs lean rodents may account for some of the differences seen in obesity-related tumor growth seen in the human condition. However, the lack of any sera differences of immune function, as measured by macrophage activity, as well as no significant differences on mitogenic proliferation on LNCaP prostate cancer cells, suggests that other mechanisms may exist to explain differences seen in obesity-related prostate tumor biology.

M2 receptors in genito-urinary smooth muscle pathology.

In vitro bladder contractions in response to cumulative carbachol doses were measured in the presence of selective muscarinic antagonists from rats which had their major pelvic ganglion bilaterally removed (denervation, DEN) or from rats in which the spinal cord was injured (SCI) via compression. DEN induced both hypertrophy (505+/-51 mg bladder weight) and a supersensitivity of the bladders to carbachol (EC50=0.7+/-0.1 uM). Some of the SCI rats regained the ability to void spontaneously (SPV). The bladders of these animals weighed 184+/-17 mg, significantly less than the bladders of non voiding rats (NV, 644+/-92 mg). The potency of carbachol was greater in bladder strips from NV SCI animals (EC50=0.54+/-0.1 uM) than either bladder strips from SPV SCI (EC50=0.93+/-0.3 microM), DEN or control (EC50=1.2+/-0.1 microM) animals. Antagonist affinities in control bladders for antagonism of carbachol induced contractions were consistent with M3 mediated contractions. Antagonist affinities in DEN bladders for 4-diphenlacetoxy-N-methylpiperidine methiodide (4-DAMP, 8.5) and para fluoro hexahydrosilodifenidol (p-F-HHSiD, 6.6); were consistent with M2 mediated contractions, although the methoctramine affinity (6.5) was consistent with M3 mediated contractions. p-F-HHSiD inhibited carbachol induced contraction with an affinity consistent with M2 receptors in bladders from NV SCI (pKb=6.4) animals and M3 receptors in bladders from SPV SCI animals (pKb=7.9). Subtype selective immunoprecipitation of muscarinic receptors revealed an increase in total and an increase in M2 receptor density with no change in M3 receptor density in bladders from DEN and NV SCI animals compared to normal or sham operated controls. M3 receptor density was lower in bladders from SPV SCI animals while the M2 receptor density was not different from control. This increase in M2 receptor density is consistent with the change in affinity of the antagonists for inhibition of carbachol induced contractions and may indicate that M2 receptors or a combination of M2 and M3 receptors directly mediate smooth muscle contraction in bladders from DEN and NV SCI rats.