OBJECTIVETo determine the effect of the area postrema (AP) of the medulla oblongata on gastrointestinal interdigestive migrating motor complex (MMC) and the plasma motilin level.

METHODSInterdigestive MMC activities of the antrum and duodenum were recorded by strain gauge implanted on the serosa of 8 conscious dogs. A cannula was intubated in femoral vein for motilin injection. The plasma motilin concentration was measured by RIA. We observed: (1) normal interdigestive MMC activity and fluctuations in plasma motilin concentration; (2) the effects of electrically damaging the AP on MMC activity and plasma motilin level; (3) whether intravenous injection of motilin could induce phase III contractions after the AP was destroyed.

RESULTS(1) Typical interdigestive MMC with phase I, II, III, and IV was recorded in normal dogs. Phase III was concurrent with the peak of plasma motilin level. (2) In damaged AP dogs, antroduodenal interdigestive MMC contractions were suppressed; cyclic, phasic and migratory pattern of MMC was disrupted. Plasma motilin concentration was decreased. Intravenous injection of motilin could not induce phase III contractions.

CONCLUSIONSThe area postrema might play an important role, which is mediated by motilin, on the regulation of interdigestive MMC.

Animals ; Dogs ; Fourth Ventricle ; physiology ; Medulla Oblongata ; physiology ; Motilin ; blood ; Myoelectric Complex, Migrating ; physiology ; Stomach ; physiology

PURPOSE: Photoplethysmography (PPG) is a noninvasive optical technology that detects changes in blood volume in the vascular system. This study aimed to investigate the possibilities of monitoring the cardiovascular system status by using PPG. MATERIALS AND METHODS: Forced hemodynamic changes were induced using cardiac stimulants; dopamine and epinephrine, and PPG components were recorded by a noninvasive method at the peripheral blood vessels. The results were compared among 6 dogs. Endotracheal intubation was performed after an intramuscular injection of 25 mg/kg ketamine sulfate, and anesthesia was maintained with 2% enflurane. After stabilizing the animals for 15 min, 16 mg/mL diluted dopamine was injected into a vein for 2 min at 20 microgram/kg.min(-1) by using an infusion pump. Thereafter, the infusion pump was stopped, and 1 mg epinephrine was injected intravenously. Fluid administration was controlled to minimize preload change in blood pressure. RESULTS: After stimulant administration, systolic blood pressure (SBP) and diastolic blood pressures (DBP) increased. The direct current (DC) component, which reflects changes in blood volume, decreased while the alternating current (AC) component, which reflects changes in vascular compliance and resistance, increased. The correlation coefficient between SBP and the foot of the DC component was 0.939 (p < 0.01), while it was 0.942 (p < 0.01) for DBP and the peak of the DC component. The AC component could predict the increase in vascular resistance from a stable pulse blood volume, even with increased pulse pressure. Conclusions: These results support the possibility that PPG components may be used for easy and noninvasive measurement of hemodynamic changes in the cardiovascular system.
Animals ; Blood Pressure/*physiology ; *Blood Pressure Monitors ; Dogs/*physiology ; Humans ; Models, Animal ; Photoplethysmography/*methods

Pulsatile blood flow plays an important role in maintaining normal vascular endothelial function. Quantitative measurement of pulsatility of artery blood pressure and blood flow in dogs and effects of enhanced external counterpulsation (EECP) on the pulsatility were taken in this study. Common carotid artery blood pressure and blood flow were measured in 6 beagle dogs that had suffered from an acute myocardial infarction 6 weeks before. A 6F tip transducer catheter was inserted into the right common carotid artery to measure blood pressure, and blood flow was measured in the left common carotid artery by an electromagnetic blood flow probe under anesthesia before and during EECP. Blood pulse pressure, pulsatility index (ratio of peak pressure to end diastolic pressure) and standard deviation of blood pressure were calculated to evaluate the pulsatility of arterial blood pressure. Blood pulse flow, pulsatility index (ratio of peak flow to trough flow) and standard deviation of blood flow were calculated to evaluate the pulsatility of blood flow. Mean vascular resistance (MVR) was calculated as MVR = mean blood pressure/mean blood flow. Blood pulse pressure, pulsatility index and standard deviation of blood pressure were elevated from 30 +/- 9 mmHg, 1.26 +/- 0.05 and 8.7 +/- 2.5 mmHg to 43 +/- 8 mmHg (P < 0.05), 1.54 +/- 0.13 and 12.4 +/- 2.0 mmHg (P < 0.05) before and during EECP, respectively. Blood pulse flow, pulsatility index and standard deviation of blood flow were elevated from 317 +/- 48 ml/min, 2.85 +/- 0.21 and 96 +/- 21 ml/min to 447 +/- 88 ml/min, 4.56 +/- 0.90 and 131 +/- 39 ml/min before and during EECP (P < 0.05). MVR was decreased from 578 +/- 72 before EECP to 476 +/- 85 Wood units during EECP(P < 0.05). These data demonstrate that EECP gives an elevation of pulsatility to blood pressure and blood flow, thus it may lead to the decrease of vascular resistance.
Animals ; Blood Pressure ; Carotid Arteries ; physiology ; Counterpulsation ; Dogs ; Hemodynamics ; Pulsatile Flow ; Regional Blood Flow ; Vascular Resistance

Penile corpus cavernosum can be seen as a special kind of vascular structure. The cause of erectile dysfunction (ED) is often related to the changes of penile vasoactive mediators which modulate the functional conditions of penile erectile tissues. The penile vasoactive mediators including angiotensin and kinins, prostaglandins, endothelins, endothelium-derived hyperpolarizing factors (EDHF), NOS and NO, RhoA/Rho-kinases, etc., may play an important role in the development of ED. Further researches on these mediators can furnish some theoretical evidence for the clinical treatment of ED.
Angiotensins ; physiology ; Animals ; Dogs ; Endothelins ; physiology ; Erectile Dysfunction ; physiopathology ; Humans ; Kinins ; physiology ; Male ; Nitric Oxide ; physiology ; Nitric Oxide Synthase ; physiology ; Penis ; blood supply ; Prostaglandins ; physiology ; Rats

OBJECTIVETo assess the significance of stroke volume variation (SVV) and intrathoracic blood volume index (ITBI) on the responsiveness to volume loading in mechanically ventilated canine with hemorrhagic shock.

METHODSHemorrhagic shock canine model was established with the modified Wiggers' method. The heart rate (HR), mean artery pressure (MAP), central venous pressure (CVP), pulmonary artery wedge pressure (PAWP), intrathoracic blood volume index (ITBI) and stroke volume variation (SVV) were investigated by Swan-Ganz catheter or PiCCO monitor. Graded volume loading (VL) was performed. Successive responsive VLs were performed (increase in SV > 5% after VL) until continuous change in SV < 5% (unresponsive) was reached.

RESULTSFourteen canines were studied and a total of 134 VLs were performed. In 94 VLs, an increase in SV of more than 5% was reached. In the other 40 VLs, increase in SV was less than 5%. The change of HR, MAP, ITBI, SVV in responsive were more than those of unresponsive after VL. The change of CVP, PAWP in responsive were less than those of unresponsive. Significant correlation was found between DeltaSV after VL and the baseline values of ITBI, SVV. No correlation was found between DeltaSV and HR, MAP, CVP, PAWP. Significant correlations were also found between DeltaSV and DeltaCVP, DeltaPAWP, DeltaITBI, DeltaSVV after fluid loading. No correlation was found between DeltaSV and DeltaHR, DeltaMAP. By using receiver operating characteristic analysis, the area under the curve were 0.872 for SVV and 0.689 for ITBI, more than those of HR, MAP, CVP, PAWP statistically. As SVV value of 9.5% or more will predict an increase in the SV of at least 5% in response to a VL with a sensitivity of 92.6% and a specificity of 82.5%.

CONCLUSIONSSVV and ITBI were more useful indicators than CVP and PAWP on the assessment of responsiveness to volume loading. SVV as a functional preload parameter and for on-line monitoring may help to improve the hemodynamic management.

Animals ; Blood Volume ; physiology ; Blood Volume Determination ; methods ; Dogs ; Female ; Male ; Shock, Hemorrhagic ; diagnosis ; physiopathology ; Stroke Volume ; physiology

This study was to determine the daily fluctuation of serum thyroxine (tT4), free thyroxine (fT4), 3,5,3'-triiodothyronine (T3) concentrations in healthy dogs. Thyroid function of these dogs was evaluated on the basis of results of TSH response test. Samples for the measurement of serum tT4, fT4, and T3 concentrations were obtained at 3- hour intervals from 8 : 00 to 20 : 00. Serum tT4, fT4, and T3 concentrations were measured by the enzyme chemiluminescent immunoassay (ECLIA). Mean T3 concentrations had no significant differences according to the sample collection time during the day. Mean tT4 and fT4 concentrations at 11 : 00 were 3.28 +/- 0.86 microgram/dl and 1.30 +/- 0.37 ng/dl, respectively and mean tT4 and fT4 at 14:00 were 3.54 +/- 1.15 microgram/dl and 1.35 +/- 0.12 ng/dl, respectively. These concentrations were significantly high compared with tT4 and fT4 concentrations at 8:00, which were 1.75 +/- 0.75 microgram/dl and 0.97 +/- 0.25 ng/dl, respectively (p < 0.05). According to the sample collection time, mean tT4 and fT4 concentrations changed with similar fluctuation during the day. Based on these results, it was considered that measurement of serum tT4 and fT4 concentrations from 11 : 00 to 14 : 00 might more easily diagnose the canine hypothyroidism in practice.
Animals ; Circadian Rhythm/physiology ; Dogs/*blood ; Female ; Immunoenzyme Techniques/veterinary ; Male ; Thyroid Function Tests/veterinary ; Thyroxine/*blood ; Triiodothyronine/*blood

A new device that allows noninvasive measurement of venous pressure has been invented in our laboratory and tested for its feasibility and validity. The device consists of four parts: 1. the air infusion system; 2. the pressure sensor gauge; 3. signal transducer and data processing system 4. the fixing apparatus. The correlation between noninvasive pressure and invasive pressure has been studied in vitro test on a saphenous vein model and in vitro test on dog's portal venous system. In vitro and vivo study, an excellent correlation between noninvasive pressure and invasive pressure was obtained(r = 0.99, P < 0.0005; r = 0.97, P < 0.005). These data suggest that the new device allows a noninvasive measurement of venous pressure especially for the large veins such as vena cava, venae pulmonales and esophageal varices.
Animals ; Blood Pressure Determination ; instrumentation ; Dogs ; Equipment Design ; In Vitro Techniques ; Venous Pressure ; physiology

The present paper aims to investigate the relation between characteristic parameters of transesophageal photoelectric pulse wave in descending aorta and ambulatory artery blood pressure. The chests of ten adult experimental dogs were performed to take the photoelectric pulse wave of descending aorta transesophageally. The concurrent femoral artery invasive blood pressure was recorded simultaneously. Stepwise regression analysis method was used to study the correlation efficient between characteristic parameters of descending aorta pulse wave (H, h, h/H, g/H, At, s, H(1 + ts/td), k)and invasive artery blood pressure. The characteristic parameters, k and h/H (ratio: 90% and 80%) was proved that they had good correlation with systolic pressure; and k, H and s (ratio: 90%, 80% and 70%), had good correlation with diastolic pressure; while k and H (ratio: 90% for both) had good correlation with mean pressure. The mean values of multiple correlation coefficients of the selected characteristic parameters of descending aorta pulse wave with systolic pressure, diastolic pressure and mean pressure of femoral artery were 0.871, 0.900 and 0.856, respectively. The characteristic parameters of descending aorta pulse wave had specific correlation with systolic pressure, diastolic pressure and mean pressure.
Animals ; Aorta, Thoracic ; physiology ; Blood Pressure ; physiology ; Blood Pressure Monitoring, Ambulatory ; methods ; Dogs ; Electrophysiologic Techniques, Cardiac ; methods ; Female ; Femoral Artery ; physiology ; Male ; Pulse Wave Analysis ; methods ; Regression Analysis

Intracranial pressure fluctuates due to heart beat, respiration, neuro-regulation, etc. Traditional intracranial pressure study focuses on the static pressure and related factors, putting emphasis on mean intracranial pressure, while paying little attention to the pulse components. This study was composed of two parts: animal experiment and theoretical analysis. The animal experiment was performed on 14 mongrel dogs, studying the variation of intracranial pressure wave form under different intracranial pressure level. The dogs were installed epidurally with latex sacculus to establish models of increased intracranial pressure. The degree of intracranial pressure and volume could be altered by changing the volume of fluid in the sacculus. During the process, pressure transducers were arranged to monitor and record the variations of the pressure of intracranial ventricle and lumbar subarachnoid cavity. The result demonstrated that, with the continual increase of intracranial pressure, intracranial pulse pressure increased correspondingly, showing a linear relationship with the change of intracranial pressure. After the sacculus was emptied and reinfused, the slope of the linear relationship was determined to be greater than the former slope. The same result was obtained in the lumbar cerebrospinal fluid pressure. Therefore, the lumbar cerebrospinal fluid pressure is consistent with the intracranial pressure. Intracranial pulse pressure is in linear relationship with mean pressure, and the slope of their linear relationship predicts the perform of intracranial autoregulation.
Animals ; Blood Pressure ; physiology ; Cerebrospinal Fluid Pressure ; physiology ; Dogs ; Female ; Intracranial Pressure ; physiology ; Male ; Monitoring, Physiologic ; methods ; Pulsatile Flow ; physiology ; Pulse

OBJECTIVETo investigate the possibility of tracheas transplantation by wrapping it in a muscle flap.

METHODSWith a dog model, a number of tracheas were separately wrapped in the unilateral sternocephalic muscle flap and the bilateral sternohyoid-sternothyroid muscle flap, and placed in the original site. The tracheas autografting was used as a control. The viability was evaluated by the examination of fiberoptic bronchoscopy, histopathology and microangiography, the measurement of tracheal mucosal blood flow and the calculation of survival rate and percentage of patency.

RESULTSThe submucosal blood flow of the transplanted tracheas was detected in the unilateral sternocephalic muscle flap group and the bilateral sternohyoid-sternothyroid muscle flap group 1 week after the surgery and gradually reached the level close to the normal in 4 weeks, while the vascular ingrowth was also shown from the wrapped muscle flap into the transplanted tracheas by using a microangiography technique. The histopathological examination demonstrated that the structure of the transplanted tracheas was quite same as the original one and its inner surface was also covered with pseudostratified columnar ciliary epithelia. However, in the control group, the mucous membranes turned black one week after the transplantation and all dogs died from the graft necrosis.

CONCLUSIONThe tracheas wrapped in a muscular flap could survive well for a long time.

Animals ; Dogs ; Epithelium ; Graft Survival ; physiology ; Necrosis ; mortality ; Regional Blood Flow ; physiology ; Surgical Flaps ; blood supply ; pathology ; Time Factors ; Trachea ; blood supply ; pathology ; transplantation ; Transplantation, Autologous