Significant Differences In Flow Rates Research Articles

The changes on salivary flow rates, buffering capacity and chromogranin A levels in adults after bariatric surgery.

This study aimed to investigate changes in salivary flow rates, buffering capacity, and salivary chromogranin A (CHGA) levels in adults undergoing bariatric surgery (BS) compared with a non-obese control group. Salivary analyses were performed on 62 participants aged over 50years, stratified into two groups matched for age and gender-individuals who had undergone bariatric surgery (BS) (n = 31) and a corresponding healthy control group (n = 31). Before saliva collection, participants completed a comprehensive 11-point visual numerical rating scale (NRS 0-10) xerostomia questionnaire, assessing subjective perceptions of two key aspects: dryness of the oral mucosa and resultant impact on oral functional ability. Three distinct saliva measurements were obtained: unstimulated whole saliva (UWS), stimulated whole saliva (SWS), and unstimulated upper labial saliva (ULS). The buffering capacity of unstimulated saliva was assessed using pH indicator strips, and concentrations of salivary Chromogranin A (CHGA) were quantified in stimulated saliva via enzyme-linked immunosorbent assay (ELISA). After BS, more than 40% of BS group patients reported xerostomia, with 16.1% experiencing only mild symptoms without significant functional impact (p = 0.009). The prevalence of xerostomia and tongue dryness was higher in the BS group compared to the control group (p = 0.028 and p = 0.025, respectively). The comparative analysis unveiled no statistically significant differences in flow rates of unstimulated upper labial saliva (ULS), unstimulated whole saliva (UWS), and stimulated whole saliva (SWS) between the control group and patients who underwent bariatric surgery. However, in patients undergone BS with xerostomia, both ULS and UWS flow rates were significantly lower than in controls with xerostomia (p = 0.014 and p = 0.007, respectively). The buffering capacity was significantly lower in patients undergone BS than in controls (p = 0.009). No differences were found between groups regarding CHGA concentration and output values, nevertheless, higher values of CHGA concentrations were significantly correlated to lower flow rates. According to the results, this study suggests that individuals undergoing BS may exhibit altered salivary buffering capacity and reduced unstimulated salivary flows in the presence of xerostomia. Additionally, the findings suggest that elevated concentration of salivary CHGA might be associated, in part, with salivary gland hypofunction. The clinical significance of this study lies in highlighting the changes in salivary functions after BS. The identified salivary alterations might be attributed to adverse effects of BS such as vomiting, gastroesophageal reflux, and dehydration. Understanding these changes is crucial for healthcare professionals involved in the care of post-BS patients, as it sheds light on potential oral health challenges that may arise as a consequence of the surgical intervention. Monitoring and managing these salivary alterations can contribute to comprehensive patient care and enhance the overall postoperative experience for individuals undergoing BS.

Estimation of Respiratory Nasal Pressure and Flow Rate Signals Using Different Respiratory Sound Features

BackgroundRespiratory sounds are associated with the flow rate, nasal flow pressure, and physical characteristics of airways. In this study, we aimed to develop the flow rate and nasal flow pressure estimation models for the clinical application, and find out the optimal feature set for estimation to achieve the optimal model performance. MethodsRespiratory sounds and flow rate were acquired from nine healthy volunteers. Respiratory sounds and nasal flow pressure were acquired from twenty-three healthy volunteers. Four types of respiratory sound features were extracted for flow rate and nasal flow pressure estimation using different estimation models. Effects of estimations using these features were evaluated using Bland-Altman analysis, estimation error, and respiratory sound feature calculation time. Besides, expiratory and inspiratory phases divided estimation errors were compared with united estimation errors. ResultsThe personalized logarithm model was selected as the optimal flow rate estimation model. Respiratory nasal flow pressure estimation based on this model was also performed. For the four different respiratory sound features, there is no statistically significant difference in flow rate and pressure estimation errors. LogEnvelope was, therefore, chosen as the optimal feature because of the lowest computational cost. In addition, for any type of respiratory sound feature, no statistically significant difference was observed between divided and united estimation errors (flow rate and pressure). ConclusionRespiratory flow rate and nasal flow pressure can be estimated accurately using respiratory sound features. Expiratory and inspiratory phases united estimation using respiratory sounds is a more reasonable estimation method than divided estimation. LogEnvelope can be used for this united respiratory flow rate and nasal flow pressure estimation with minimum computational cost and acceptable estimation error.

Peripheral venous catheter collection of immune effector cells and hematopoietic stem cells is feasible and safe in older pediatric patients.

The Collection of hematopoietic stem cells (HSC) and immune effector cells (IEC) has unique challenges in children. To maintain adequate blood flow, central venous catheters (CVCs) remain the standard of care in many centers, but are associated with procedural risks and increased resource utilization. The goal of this study was to determine feasibility and safety of peripheral venous catheter (PVC) cell collection in older children. Patients and donors requiring venous access with weight >25 kg, age >8 years were screened for PVC collection via 18G PVCs. Those with poor venous access (on history/exam/pre-screening ultrasound) or unable to maintain suitable procedural position were excluded. Comparison was made to CVC collections in a matched patient cohort. Thirty-eight individuals were screened and met age/weight criteria for PVC collection. Five did not have PVC collection attempted due to poor access (n= 4) or behavioral concerns (n= 1). Thirty-three had PVC collection attempt (HSC=22; IEC=11) with median age 15.3year (range 9.7-18.0) and weight 58.5kg (range 27.9-115.4). Thirty-two of 33 (97%) patients were collected successfully by PVC without adverse events. Comparing PVC to matched CVC collection cohort (n= 18), there was no significant difference in flow rate (48.2mL/h vs 53.9mL/h, p=0.12), collection time (266 min vs 262 min, p=0.85) or collection efficiency (IEC/CD3 60.9% vs 60.8% p=0.99; HSC/CD34 53.6% vs 41.3% p=0.05). PVC collection of HSC and IEC is feasible and safe in older children with comparable collection efficiency to CVC collections. Ultrasound screening may reduce failure rates. PVC collections can reduce the risk of CVC insertions and associated healthcare costs.

Effect of peach gum polysaccharide, a new fat substitute, on sensory properties of skimmed milk

Carbohydrate-based fat substitutes are of growing interest, because as well as maintaining the flavour of food without increasing costs, they have health-friendly properties. This study examined the effect of adding peach gum polysaccharide (PGP) on the rheological friction behaviour, structure and sensory properties of skimmed milk. Skimmed milk containing 0.5% PGP showed similar rheological behaviour to full-fat milk, i.e., there was no significant difference in flow rate (n and k) or viscoelasticity (G′, G″ and η∗ at 50 rad s−1; P > 0.05). Similarly, tribological testing showed no significant difference in tribological parameters (the average surface roughness was 2.390 and 2.287, and the root mean square was 2.908 and 2.855, respectively). Electron microscopy showed that PGP stabilised the structure of milk. Skimmed milk containing 0.5% PGP showed a similar creamy mouthfeel to full-fat milk. Therefore, PGP has potential to become a new polysaccharide-based fat substitute.

Effect of Formula Type and Preparation on International Dysphagia Diet Standardisation Initiative Thickness Level and Milk Flow Rates From Bottle Teats.

Purpose The purpose of this study was to evaluate the effect of infant formula type and preparation (i.e., ready-to-feed vs. powder) on International Dysphagia Diet Standardisation Initiative (IDDSI) thickness level and milk flow rates from bottle teats/nipples. Method The ready-to-feed and powder formulations of the following products were tested for IDDSI thickness level, using IDDSI guidelines, and for milk flow rate, using established flow testing methods: Similac Advance, Similac For Spit-Up, Enfamil Infant, and Enfamil A.R. Analysis of variance was used to compare flow rates among formula types/preparations. Results Enfamil A.R. ready-to-feed was classified as IDDSI "slightly thick." All other formula types/preparations were found to be IDDSI "thin" liquids. The standard infant formulas (Similac Advance and Enfamil Infant) had comparable flow rates to each other, regardless of preparation (ready-to-feed and powder). The gastroesophageal reflux-specific formulas (Similac For Spit-Up and Enfamil A.R.) had slower flow rates than the standard formulas; within this category, there were significant differences in flow rates between ready-to-feed and powder. Enfamil A.R. powder had the slowest flow rate, but was the most variable. Conclusion For infants with difficulty coordinating sucking, swallowing, and breathing, clinicians and parents should consider the impact that changes to infant formula type and preparation may have on the infant's ability to safely feed.

Anticariogenic efficacy of a saliva biomimetic in head-and-neck cancer patients undergoing radiotherapy.

The aim of this study was to investigate the effect of treatment with the saliva biomimetic, casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and SnF2 /NaF compared with SnF2 /NaF alone on coronal surface caries progression in head-and-neck cancer patients undergoing radiotherapy. Twenty-four participants were randomized into two groups. Both groups used 0.4% SnF2 gel and a 0.32% NaF toothpaste; the test group also applied a crème containing 10% CPP-ACP three times daily while the control group used an identical crème without CPP-ACP (placebo). Resting saliva flow rate and saliva fluoride concentrations were determined. Caries status was assessed using ICDASII at baseline and 12-weeks postradiotherapy. Data were statistically analysed using a linear mixed effects model. Both groups showed significantly reduced resting saliva flow rate (P < 0.001) postradiotherapy. There were no significant differences in flow rates and fluoride concentration between groups. The CPP-ACP group exhibited a significant (P < 0.05) 51% reduction in coronal surface caries progression compared with the placebo group. Resting salivary flow rate was significantly reduced in head-and-neck cancer patients following radiotherapy and use of CPP-ACP with SnF2 /NaF significantly lowered caries progression compared with SnF2 /NaF alone.

Hydraulic performance of new and used self-compensating micro-sprinklers

From the technical and economic perspectives, it is imperative that irrigation systems have extensive durability and high uniformity of application. The objective of this study was to compare the hydraulic performance of new and used (9 years of use with 4265 h of operation) self-compensating micro-sprinklers of the SuperNet LR model. The study was performed in a laboratory to evaluate flow in the range of pressure compensation, coefficient of manufacturing variation or discharge (CVF and CVQ), wetting pattern, distribution uniformity coefficient (DUC), and Christiansen uniformity coefficient (CUC).The new and used micro-sprinklers did not differ in CVF and CVQ, and were rated as excellent; they also did not differ in CUC or DUC. The coverage diameters of the new and used micro-sprinklers were the same as those given in the manufacturer’s catalog. There were no significant differences in the flow rates of the new and used micro-sprinklers when subjected to the same pressure, but significant differences in flow rate were observed within the range of pressure compensation. When installed in an irrigation system, the useful life of micro-sprinklers can be considered to be greater than 9 years with 4265 h of operation.

The effect of different mixing methods on the flow rate and compressive strength of mineral trioxide aggregate and calcium-enriched mixture.

Flow rate (FR) and compressive strength (CS) are important properties of endodontic biomaterials that may be affected by various mixing methods. The aim of this experimental study was to evaluate the effect of different mixing methods on these properties of mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) cement. Hand, amalgamator and ultrasonic techniques were used to mix both biomaterials. Then 0.5 mL of each mixture was placed on a glass slab to measure FR. The second glass slab (100 g) was placed on the samples and 180 sec after the initiation of mixing a 100-g force was applied on it for 10 min. After 10 min, the load was removed, and the minimum and maximum diameters of the sample disks were measured. To measure the CS, 6 sample of each group were placed in steel molds and were then stored in distilled water for 21 h and 21 days. Afterwards, the CS test was performed. Data were analyzed with multi-variant ANOVA and post hoc Tukey tests. The level of significance was set at 0.05. There were significant differences in FR of MTA and CEM cement with different mixing techniques (P<0.05). In the MTA group, none of the mixing techniques exhibited a significant effect on CS (P>0.05); however, in CEM group the CS at 21-h and 21-day intervals was higher with the hand technique (P<0.05). Mixing methods affected the flowability of both biomaterials and compressive strength of CEM cement.

The flow of two zinc oxide-eugenol-based endodontic sealers

Endodontic sealers (ES) for obturation are usually prepared with a slight variation of their components both on purpose or unintentionally. Considering that fact, as well as a frequent use of compaction techniques with the applied force to gutta-percha and ES of 1-3 kg, the aim of this study was to investigate the flow of two zinc-oxide eugenol ES in regard to the applied force and a variation of sealer's components. The experimental group samples of both ES were prepared according to the manufacturer's instructions, applied between pair of glass slabs and loaded by weights of 1 and 2 kg, respectively (American National Standard, Specification No. 57). Some samples of one ES were prepared as thick consistency with 10% more powder and some as thin mixture with 10% less powder than the standard prescription. These semples had been exposed to the load of 2 kg. The control group included samples of both ES prepared as standard prescription but exposed to the weight of one glass slab only. The spread ES appeared as a regular circle 10 min upon mixing and weighting. Measuring of the circle diameter was done by an orthodontic ruler. The flow of the used ES was considered the function of its spread diameter. Application of 1 vs 2 kg load for both regularly mixed sealers in the scope of disk diameter (flow) was statistically insignificant (p > 0.05). This means that the stated null hypothesis that there would be no significant difference in flow rate among the regularly mixed sealers at the level of alpha = 0.05 is accepted. The findings about difference in the disk diameter in regard to mixing variation of Endomethasone indicate that the null hypothesis that there would be no significant difference in flow rate between the regular and thick mixed mass at the level of alpha = 0.05 is accepted. In the comparison of regular and thin mix a significant difference was noted and the null hypotesis is rejected (p < 0.01). The control group results displayed Roth 801 as less viscous than Endomethasone sealer (p < 0.01). Application of 1 or 2 kg pressure on the samples of both exposed sealers does not significantly affect the flow values as well as comparison of the regular to thick consistency of Endomethasone while comparison of its regular to thin mass shows a significant difference.

Patient-Specific Modeling and Multi-Scale Blood Simulation for Computational Hemodynamic Study on the Human Cerebrovascular System

To develop a targeted drug delivery system for cerebrovascular disorders such as stroke, it is important to obtain detailed information on flow rates and hemodynamics of the human cerebrovascular system for individual patients. A patient-specific integrated numerical simulation system has been developed by the authors such that vascular geometry is constructed from medical images such as magnetic resonance imaging (MRI) or computed tomography (CT) data, and computational conditions are modeled mathematically to represent the realistic in vivo environments. In general, the three-dimensional numerical simulation using a patient-specific model is conducted only for a localized diseased region with atherosclerosis or an aneurysm. Although the analysis region is only a part of the circulatory system, the simulation should include the effects from the entire circulatory system. Since the peripheral network determines the flow distributions in the cerebrovascular system, the paper reviews the recent simulation methods to take into account the network by coupling the image-based three-dimensional simulation with a one- and zero-dimensional simulations as an outflow boundary condition The paper shows the mathematical modeling of the multi-scale outflow boundary condition and its applications to patient- specific models of the arterial circle of Willis. The results are compared to those using the conventional, free-stream boundary condition. As a result, the multi-scale outflow boundary condition shows a significant difference in flow rate of each artery and in flow distribution in the arterial circle of Willis.

Physicochemical characteristic of unstimulated and stimulated saliva with different chewing gum stimulation

stimulate salivary flow, increase in saliva flow lead to more frequent replenishment and greater supply of antibacterial factors, saline, buffers, minerals and other beneficial constituents, increase pH and buffer capacity of whole saliva. The aim of the present study was to investigate the effect of different chewing gums on the salivary constituents including some elements (Magnesium, Calcium, Copper and Zinc)(chemical),PH and flow rate(physical)characteristic. Materials and Methods: Saliva samples was collected from dental students/college of dentistry 23 age stimulated by three types of chewing gum (mastic, Arabic, sugar) and control group (unstimulated saliva), pH and saliva flow rate was recorded for four groups. Biochemical analysis was assessed for some salivary elements, (Magnesium, Calcium, Copper, and Zinc) and its relation with different chewing gum and control group. Student's t-test, ANOVA and LSD test was used for statistical analysis. Also mean and standard deviation was recorded. Results: Mean value of pH was found to be high in three types of chewing gum with highly significant difference comparing with control group. A significant difference in flow rate was found between control and sugared gum group. Mg and Ca ione was found to be highly significant between mastic gum group and other three groups , as well as highly significant difference was recorded among four groups of saliva in Cu ione, while no significant difference was showed between Zn ione and four groups. Conclusion: Chewing gum include natural (mastic and Arabic) and sugared was increases salivary pH. Use of chewing gum especially mastic and Arabic can enhance the remineralizing potential of the mouth, probably by stimulating salivary flow which may lead to rise salivary elements.

Evaluation of a New Device for the Intraoperative Assessment of Coronary Artery Bypasses Grafting

The aim of this study was to evaluate a new flow analyze device that can intraoperatively measure compliance and resistance of coronary artery bypass grafting (CABG) by the parameter identification method. Subjects were 95 patients who underwent CABG. Angiography soon after surgery confirmed patency in 90 grafts and graft failure in 5 grafts. Variables of aortic pressure and the graft flow were entered into this new device that includes a mathematical coronary circulation model to extrapolate other information the data; thus, we can estimate intraoperative flow rate, resistance, and compliance. Flow rate, resistance, and compliance were compared between patent and failed graft groups and among three different type grafts. There were no differences in flow rate, resistance, and compliance among the three grafts types. Between the patent and failed graft groups, there were statistically significant differences in flow rate and resistance, and compliance tended to be lower for the failed graft group. By measuring graft resistance and compliance, this new device is useful for evaluating graft performance during CABG.

Glucose-dependent blood flow dynamics in murine pancreatic islets in vivo

Pancreatic islets are highly vascularized and arranged so that regions containing beta-cells are distinct from those containing other cell types. Although islet blood flow has been studied extensively, little is known about the dynamics of islet blood flow during hypoglycemia or hyperglycemia. To investigate changes in islet blood flow as a function of blood glucose level, we clamped blood glucose sequentially at hyperglycemic ( approximately 300 mg/dl or 16.8 mM) and hypoglycemic ( approximately 50 mg/dl or 2.8 mM) levels while simultaneously imaging intraislet blood flow in mouse models that express green fluorescent protein in the beta-cells or yellow fluorescent protein in the alpha-cells. Using line scanning confocal microscopy, in vivo blood flow was assayed after intravenous injection of fluorescent dextran or sulforhodamine-labeled red blood cells. Regardless of the sequence of hypoglycemia and hyperglycemia, islet blood flow is faster during hyperglycemia, and apparent blood volume is greater during hyperglycemia than during hypoglycemia. However, there is no change in the order of perfusion of different islet endocrine cell types in hypoglycemia compared with hyperglycemia, with the islet core of beta-cells usually perfused first. In contrast to the results in islets, there was no significant difference in flow rate in the exocrine pancreas during hyperglycemia compared with hypoglycemia. These results indicate that glucose differentially regulates blood flow in the pancreatic islet vasculature independently of blood flow in the rest of the pancreas.

Water-flow variation and pharmacoepidemiology of tetracycline hydrochloride administration via drinking water in swine finishing farms

To evaluate variation of drinking-water flow rates in swine finishing barns and the relationship between drinker flow rate and plasma tetracycline concentrations in pigs housed in different pens. Cross-sectional (phase 1) and cohort (phase 2) studies. 13 swine finishing farms (100 barns with 7,122 drinkers) in phase 1 and 100 finishing-stage pigs on 2 finishing farms (1 barn/farm) in phase 2. In phase 1, farms were evaluated for water-flow variation, taking into account the following variables: position of drinkers within the barn, type of drinker (swing or mounted), pig medication status, existence of designated sick pen, and existence of leakage from the waterline. In phase 2, blood samples were collected from 50 pigs/barn (40 healthy and 10 sick pigs) in 2 farms at 0, 4, 8, 24, 48, and 72 hours after initiation of water-administered tetracycline HCl (estimated dosage, 22 mg/kg [10 mg/lb]). Plasma tetracycline concentrations were measured via ultraperformance liquid chromatography. Mean farm drinker flow rates ranged from 1.44 to 2.77 L/min. Significant differences in flow rates existed according to drinker type and whether tetracycline was included in the water. Mean drinker flow rates and plasma tetracycline concentrations were significantly different between the 2 farms but were not different between healthy and sick pigs. The plasma tetracycline concentrations were typically < 0.3 microg/mL. Many factors affected drinker flow rates and therefore the amount of medication pigs might have received. Medication of pigs with tetracycline through water as performed in this study had questionable therapeutic value.

Salivary flow rate and acute-phase proteins in Bell's palsy

The flow rate of extra-parotid and parotid saliva was compared in patients with Bell's palsy and in healthy volunteers. Samples were analysed for the concentration of total protein and seven acute-phase proteins. There was no difference between younger and older patients with regard to oral status, salivary flow rate, total protein or acute-phase proteins, in either extra-parotid or parotid saliva. No significant difference in flow rate for both extra-parotid and parotid saliva was found in the Bell's palsy patients in comparison with the controls. In the patients the salivary flow rate from the parotid gland on the paralysed side was slightly lower than on the healthy side, but not to a significant extent. The quantity of total protein was lower in the extra-parotid saliva in the patient group; there were no differences between the two groups with regard to parotid saliva. We were able to demonstrate small amounts of various acute-phase proteins in the control group. In the patients we found higher quantities per minute of acute-phase proteins in both extra-parotid saliva and parotid saliva than in the controls. In extra-parotid saliva there were significant differences in haptoglobulin, alpha 2-macroglobulin, C3-complement factor and ceruloplasmin; in parotid saliva the differences in haptoglobulin and ceruloplasmin were significant. However, there was a large inter individual variation in both groups studied. In the patient group no significant difference in the secretion of acute-phase proteins from the parotid gland could be demonstrated between the paralysed side and the healthy side.(ABSTRACT TRUNCATED AT 250 WORDS)

On permeation effects of aqueous solutions through non-mature pastes of portland-pozzolana cement

Portland-pozzolana cement pastes hydrated at 1,2 and 3 days were investigated for permeability tests. They were carried out with distilled water or lime-saturated solutions. Significant differences in flow rates, depending on the period of curing of cement pastes and on the type of testing solution, have been observed. Among the effects that influence the permeation process, an osmotic pressure that originates when distilled water is forced through disk-shaped specimen, has been considered.

Noninvasive blood flow measurement in expanded polytetrafluoroethylene grafts for hemodialysis access

Volume flow rates were measured in 31 expanded polytetrafluoroethylene grafts (6 mm) of 26 patients undergoing hemodialysis. Flow was calculated from the known access graft diameter and by measurement of the mean Doppler shift frequency waveform. Overall flow rates were 750 ± 383 ml/min (range, 0 to 1921 ml/min). There was no difference in flow between grafts anastomosed to either antecubital or upper arm veins but there was a significant difference in flow rate between straight and loop grafts (652 and 914 ml/min) and between grafts anastomosed to the radial, distal brachial, and proximal brachial arteries (648, 876, and 1169 ml/min, respectively). Flow rates measured during a preocclusive 14-day period in five grafts were significantly lower than flow rates in grafts that remained patent for at least 2 weeks following examination (307 ± 172 vs. 849 ± 346 ml/min). This is a safe, repeatable noninvasive measure of access graft hemodynamics, which may be useful as a functional monitor and a warning of impending failure.

Age-related Salivary Flow Rate Changes in Controls and Patients with Oral Lichen Planus

Unstimulated whole saliva and stimulated whole, parotid, and labial minor gland saliva samples were collected from 25 patients with oral lichen planus and from 25 age- and sex-matched controls between the ages of 25 and 87 years. All subjects did not smoke or chew tobacco, had no serious illnesses, and were unmedicated. There were no significant differences in flow rates between the two groups. However, a significant age-related decrease in labial minor gland saliva flow rate was found in both the lichen planus group and the controls. Flow rates of unstimulated and stimulated whole saliva and stimulated parotid saliva were not related to age in either group.

Lung volumes and flow rates in black and white subjects

Lapp, N. L., Amandus, H. E., Hall, R., and Morgan, W. K. C. (1974).Thorax, 29, 185-188. Lung volumes and flow rates in black and white subjects. It has been known for some time that the vital capacity and forced expiratory volume in one second of black subjects are about 12% lower than those of whites of the same age and height. In the present study, total lung capacity and residual volume were also shown to be decreased by about the same percentage. Expiratory flow rates were similarly decreased, but when the difference in lung size was evened out by matching black and white subjects of the same total lung capacity, no significant differences in flow rates were observed.

Absence of vasoactive and cardiotropic substances in coronary sinus blood of dogs.

Elucidation of the mechanism by which coronary flow is regulated has been attempted. Substances with coronary vasodilator or vasoconstrictor properties as well as those with inotropic or chronotropic effects on isolated frog hearts were sought in the coronary sinus blood of dogs. Blood draining normal, hypoxic or "overperfused" hearts was oxygenated in a dog lung or on a screen and perfused at a controlled pressure through a rotameter into a test coronary artery of the same or second dog; unoxygenated sinus blood was also perfused into an isolated beating frog heart connected to record heart rate and amplitude of contraction. No significant differences in flow rates were observed when the test artery was perfused with oxygenated coronary sinus blood as compared to flows metered during perfusion of the artery with arterial blood. Similarly, perfusion of unoxygenated coronary sinus blood into the isolated frog heart did not affect the rate or amplitude of contraction recorded during perfusion of the heart with arterial blood. These experiments, therefore, failed to demonstrate substances having vasoactive, inotropic, or chronotropic properties in the blood draining normal, hypoxic or "overperfused" dog hearts.