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PubMed1986

Transient immunoregulatory perturbation during the acute phase of rheumatic fever.

An abnormal immune response directed at streptococcal antigen is currently thought to be involved in the development of autoimmune phenomena in rheumatic fever (RF). We studied T-cell subsets using the OKT monoclonal antibodies in 13 patients with newly-diagnosed RF. No difference was found in the total number of T cells or in the proportion of helper T cells (OKT4+) at the acute phase (56.6 +/- 6.9) as compared to the recovery phase (55.2 +/- 9.2). However, a significantly decreased proportion of suppressor T cells (OKT8+) was observed during the acute phase (17.2 +/- 6) as compared to the recovery phase (26.4 +/- 5.3) (p less than 0.001). The T4/T8 ratio was significantly higher during the initial phase (3.65 +/- 1.04) and returned to normal later (2.12 +/- 0.39) (p less than 0.002). The results of our study indicate that in the acute phase of RF many patients had low levels of suppressor T cells which return to normal after recovery. Thus, reduced proportion of suppressor T cells might be an indicator for the active phase of RF. Decreased suppressor cell activity may also be involved in the development of autoimmune phenomena in RF.

Acute Disease↗
PubMed1996

Endothelial cells of the rat brain vasculature express cyclooxygenase-2 mRNA in response to systemic interleukin-1 beta: a possible site of prostaglandin synthesis responsible for fever.

We previously showed that intraperitoneal injection of lipopolysaccharide induced cyclooxygenase-2 (COX-2) mRNA in as yet unidentified cells of blood vessels and leptomeninges in the rat brain and proposed a possible role of these cells as the source of prostaglandin E2 in the genesis of fever (Cao et al., Brain Res., 697 (1995) 187-196). In the present study, to proceed further with this line of research, we addressed the following two questions: first, does a pyrogenic dose of interleukin-1 beta (IL-1 beta), an endogenous pyrogen, induce COX-2 mRNA in the brain blood vessels and leptomeninges? Secondly, if it does, what type of cells are positive for COX-2 mRNA? Intraperitoneal injection of recombinant human IL-1 beta (30 micrograms/kg) induced fever in rats and an in situ hybridization study revealed that faint but significant COX-2 mRNA signals appeared in the blood vessels and leptomeninges at 1.5 h after the injection (the early rising phase of fever). The mRNA signals increased in number and intensity at 4 h (early plateau phase), decreased at 6.5 h (early recovery phase), and completely disappeared by 10 h after the injection (late recovery phase). The COX-2 mRNA positive cells in the blood vessels were likely to be the endothelial cells since the corresponding cells in the adjacent mirror-imaged section also expressed mRNAs for intracellular adhesion molecule-1 and the type-I interleukin-1 receptor, although those in the leptomeninges still remained unidentified. These results imply that circulating IL-1 beta acts on its receptor on the endothelial cells of the brain vasculature to induce COX-2 mRNA, which is possibly responsible for the elevated level of PGE2 seen during fever.

Animals↗
PubMed1992

Recovery of cognitive functions after anaesthesia with desflurane or isoflurane and nitrous oxide.

We studied recovery in 25 adult patients, ASA I, undergoing elective orthopaedic procedures after anaesthesia with 0.65 MAC desflurane (n = 16) or isoflurane (n = 9) with 60% nitrous oxide in oxygen. Early emergence from anaesthesia was assessed in the operating room by measuring time to spontaneous movement, cough, response to painful pinch, tracheal extubation, opening of the eyes and stating correct age, name and body parts. The return of cognitive functions in the late recovery phase was assessed in the post-anaesthesia care unit (PACU) by post-anaesthesia recovery scores (PARS), the Trieger dot test (TDT), and the digit substitution test (DST). In the early recovery phase, time to tracheal extubation, opening eyes, telling correct name, age and body parts occurred significantly faster in the desflurane group than in the isoflurane group (P < 0.05). The mean "triple orientation" time (to name, age, body parts) was 10.9 (SEM 0.9) min for desflurane, compared with 18.6 (2.5) min for isoflurane (P < 0.01). In the late recovery phase, desflurane patients had significantly greater PARS, more correct responses to the DST and fewer error responses to the TDT. Recovery times were not increased by increased duration of desflurane anaesthesia. The desflurane patients showed no delirium, minimal sedation and less shivering during the entire postoperative course. We conclude that desflurane anaesthesia was superior to isoflurane anaesthesia, not only in emergence, but also in the recovery of cognitive functions.

Adolescent↗
PubMed2003

Prognostic value of cyclic GMP in patients undergoing allogeneic bone marrow transplantation after conditioning with total body irradiation.

This study was performed to investigate whether measurement of cyclic GMP (cGMP), a marker for nitric oxide production, before and after allogeneic bone marrow transplantation (BMT) with total body irradiation (TBI) conditioning was of prognostic value. cGMP levels were monitored in 23 consecutive patients who received TBI as conditioning for BMT, and were compared with the outcome. cGMP became positive during the aplastic phase after BMT in 12 patients. In nine of these 12 patients, cGMP level decreased during the recovery phase. Eight of the nine patients survived, one dying after relapse. In three other patients, the cGMP level continued to increase even during the recovery phase and they died of severe complications. cGMP became positive on day 0 of BMT and during the leukocyte recovery phase after BMT in two and seven of the 23 patients, respectively. Subsequently, all patients died of severe complications. The two patients who were negative for cGMP both before and after BMT survived without complications. These results suggest that monitoring cGMP from early after BMT may be useful for predicting outcome and that it may be a useful prognostic marker.

Adolescent↗
PubMed1993

Effects of asphyxia on the fetal lamb brain.

OBJECTIVE: Our purpose was to study the effect of fetal asphyxia on the release of hypoxanthine and xanthine in cerebrospinal fluid and on brain histologic characteristics. STUDY DESIGN: In seven fetal lambs (3 to 5 days after surgery, gestational age 124.3 +/- 2.6 days) asphyxia was induced by restriction of uterine blood flow. RESULTS: Fetal pH and base excess were reduced to 6.99 +/- 0.02 and -17.6 +/- 0.9 mmol/L, respectively. Cerebral blood flow increased during asphyxia and returned to normal in the recovery phase. Maximum concentrations of cerebrospinal fluid hypoxanthine and xanthine were reached in the normoxemic recovery phase. This high level of substrates during normoxemia facilitates oxygen free radical formation and may thus aggravate postasphyctic brain damage. Histologic evaluation of the brain 3 days after the insult showed a variable degree of edema. Coagulative neuronal changes, characteristic of irreversible cell death, were only occasionally detected. These changes were most obvious in the Purkinje cells of the cerebellum. CONCLUSIONS: Fetal asphyxia induced by uterine blood flow restriction is associated with high levels of cerebrospinal fluid hypoxanthine and xanthine in the recovery phase. Microscopically detectable brain damage, although not extensive, is mainly located in the cerebellum.

Animals↗
PubMed1999

Evolution of single kidney glomerular filtration rate in urinary tract infection.

The aim of this study was to evaluate renal function during the acute phase of symptomatic urinary tract infection and the changes observed several months later. Overall glomerular filtration rate (GFR) as well as single kidney GFR (SKGFR) were calculated using the combination of a left/right uptake ratio obtained from technetium 99m-dimercaptosuccinic acid (DMSA) scintigraphy and 51chromium-EDTA plasma clearance. Forty-four patients with obvious unilateral or bilateral DMSA abnormalities were studied. In patients with unilateral lesions, both the overall GFR and the SKGFR were significantly higher during the acute phase of infection than several months later, on the abnormal side as well as the normal side. The relative percentage uptake was lower on the abnormal side than the normal side, obviously due to loss of functional parenchyma. This percentage increased significantly during the recovery phase, reflecting the total or partial healing of the renal lesions, despite the decrease of the corresponding SKGFR. However, during both the acute and the recovery phase, the relative percentage uptake of the abnormal kidney was in the normal range and often close to 50%. In patients with bilateral lesions, no significant changes were observed between the acute phase and the recovery phase.

Adolescent↗
PubMed1994

Force responses to rapid length changes in single intact cells from frog heart.

1. Force transients in response to step perturbations in length were recorded in intact atrial cells from frog heart at various temperatures (6-15 degrees C). Length changes of various sizes and in either direction, complete in 0.5 ms, were applied to single myocytes near slack length (initial sarcomere length 2.1-2.2 microns) just before the peak of an isometric twitch. The frequency response of the force transducers used was 2-4 kHz in Ringer solution. 2. An early quick force recovery phase was clearly observed after the elastic force response to the length step and before the start of much slower recovery processes. The quick recovery phase became progressively faster with larger shortening steps and was almost as fast as that originally described in intact frog skeletal muscle fibres (rate constants above 1000 s-1 in large releases at 10 degrees C). 3. The force-extension relation determined at the end of the length change (T1 curve) indicates that an instantaneous shortening of 0.5-0.6% of the initial cell length (L0) brings the force to zero. The force--extension relation determined at the end of the quick recovery phase (T2 curve) showed that the early recovery leads to an almost complete restoration of the original force with small stretches and releases (up to 0.3% L0) and that it becomes negligible in shortening steps of about 1.4% L0. 4. The results suggest that the mechanical properties of attached cross-bridges and the rate of transitions between attached cross-bridge states are approximately the same in frog atrial cells and fast skeletal muscle fibres.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Subacute toxicity study of miporamicin in rats by twenty-eight-day administration in feed].

A 28-day oral dosage test of miporamicin (MPM), a new macrolide antibiotic, was performed to assess its toxicologic potential in groups of male and female rats receiving the compound in feed. Five graded dosage levels of 0, 3,200, 8,000, 20,000, and 50,000 ppm were employed for treatment with MPM in feed and the treatment period was followed by a 28-day recovery phase observation period. 1. No deaths occurred throughout the course of the experiment. Animals receiving 50,000 ppm developed signs: ruffled hair coat and emaciation, which disappeared following withdrawal of the drug. 2. The MPM-50,000 group displayed depression of weight gain and decrease of feed and water intake during the treatment period. During the posttreatment recovery phase observation period the animals showed recovery in weight gain rate as well as in feed and water intake. 3. The achieved compound dosage was 273 mg/kg/day in males and 288 mg/kg/day in females in the MPM-3,200 group, 721 and 773 mg/kg/day respectively in the MPM-8,000 group, 1,738 and 1,856 mg/kg/day in the MPM-20,000 group, and 3,405 and 3,611 mg/kg/day in the MPM-50,000 group. 4. Hematological examinations revealed low values for RBC, WBC, hematocrit and hemoglobin concentration and decreased platelet counts in the MPM-50,000 group, which were considered to be due to the decreased feed intake. These changes disappeared or abated following withdrawal. 5. Of various serum biochemical parameters assessed, total protein, albumin, glucose and triglycerides showed lowered values in the MPM-50,000 group. All these changes were considered to be attributable to the decreased feed intake. During the ensuing recovery phase observation period, all these parameters showed restoration or abatement in parallel with the recovery in feed intake. 6. Urine analysis disclosed decrease of urine volume, lowered electrolyte concentration and elevation of urine osmolarity in the MPM-20,000 and the MPM-50,000 groups. These changes were considered to be secondary to cecal enlargement which is commonly seen with antibiotic medication, or to the decreased feed and water intake. Following drug withdrawal, all these changes disappeared with the recovery in feed and water intake and abatement of cecal hyperplasia. 7. At terminal necropsy, diminution of body fat and atrophy of the spleen and thymus that correlated with emaciation were noted in the MPM-50,000 group. Dose-related enlargement of the caecum was also noted in the treated groups. All these changes disappeared or abated following withdrawal.(ABSTRACT TRUNCATED AT 400 WORDS)

Administration, Oral↗
PubMed1984

Rod light response augmented by active phosphodiesterase.

Light activates rod outer segment (ROS) phosphodiesterase (PDEase), as shown by previous biochemical and physiological studies. We have further investigated the role of PDEase in this system by injecting trypsin-activated PDEase, purified from bovine ROS, into single ROS of the isolated retina of the toad Bufo marinus. Injection of about 300 molecules of activated PDEase in darkness is without immediate detectable effect, as measured by intracellular membrane-voltage recording. The effect of the activated PDEase injections only becomes evident after illumination. The light response is augmented; kinetics of repolarization are slowed. We conclude that this augmentation of the light-dependent hyperpolarization results from the hydrolysis of endogenous cyclic GMP caused by injected PDEase. These results provide evidence that PDEase affects light-dependent channels of the vertebrate scotopic photoreceptors but do not specify whether the effects are exercised for the initial hyperpolarizing phase of the receptor potential and for the recovery phase or only for the recovery phase.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1983

Increased factor VIII related antigen in cerebral thrombosis.

Changes of Factor VIII related antigen (FVIIIR:Ag) were measured in patients with cerebral thrombosis on day 1-15 (125 cases), 16-45 (acute reaction phase, 70 cases), and during 1.5-5 months (recovery phase, 29 cases) after onset of the disease. FVIIIR:Ag was significantly (P less than 0.001) increased in both acute and recovery phase as compared to 108 healthy controls, although slightly decreased in recovery than in acute phase. The persistently high FVIIIR:Ag levels in acute phase are unlikely to be caused by the so-called acute phase reaction but are probably due to increased synthesis and endothelial changes in atherosclerotic lesions releasing FVIIIR:Ag from its endothelial pool. It suggested that increased FVIIIR:Ag mainly reflects the degree of vascular involvement and it may be used as a marker (or indicator) of arterial endothelial injury in patients with cerebral thrombosis.

Acute Disease↗
PubMed2002

Physiological and production responses to feeding schedule in lactating dairy cows exposed to short-term, moderate heat stress.

The objective of this research was to characterize the production responses of lactating dairy cows during and after short-term, moderate heat exposure, and to determine whether evening (p.m.) feeding would alleviate the associated production losses. In a two-period, cross-over design, eight mature lactating cows were fed a total mixed ration at either 0830 or 2030 h. Each 15-d period consisted of a 5-d thermoneutral phase, a 5-d heat stress phase and a 5-d thermoneutral recovery phase. Mean daily vaginal temperature and respiration rate increased by 0.6 +/- 0.04 degrees C and 27 +/- 1.3 breaths/min, respectively, during short-term heat exposure. Daily dry matter intake, milk yield and solids-not-fat were depressed by 1.4 +/- 0.13 kg, 1.7 +/- 0.32 kg and 0.07 +/- 0.023%, respectively, during heat exposure. During the recovery phase, dry matter intake remained depressed, milk protein declined by 0.05 +/- 0.020%, and daily milk yield exhibited a further decline of 1.2 +/- 0.32 kg. Time of feeding had no effect on vaginal temperature, respiration rate, dry matter intake, water intake, milk yield, fat-corrected milk, protein percent, solids-non-fat percent or somatic cell count during heat exposure or during the recovery period that followed. Fat percent was, however, significantly lower in p.m.-fed animals. These data indicate that short-term, moderate heat stress, which occurs during the spring and summer months in Canada and the Northern United States, will significantly decrease production in the lactating cow. Shifting from morning to evening feeding did not alleviate production losses associated with this type of heat stress.

Animal Feed↗
PubMed1990

Correlation of pancreatic enzyme levels with the patient's recovery from acute edematous pancreatitis.

Levels of total amylase, pancreatic isoamylase, lipase and immunoreactive trypsin were measured in 27 consecutive patients with noncomplicated (methemalbumin negative, no pseudocysts on ultrasound) acute pancreatitis during the acute, subacute, and recovery phases. At the beginning of the recovery phase (no pain, start of oral food intake), amylase and pancreatic isoamylase were below normal, whereas lipase (12% of the patients) and especially trypsin (52% of the patients) were still three times above the upper limit of normal. None of the patients showed a relapse of pain at the time of oral food intake. The conclusion is that amylase and pancreatic isoamylase reflect more accurately the patient's recovery pattern in acute pancreatitis than the other enzymes. Trypsin, however, may be significant in cases of delayed diagnosis. Thus, the decision to start oral food intake should be based on the patient's clinical state rather than on pancreatic enzyme levels.

Acute Disease↗
PubMedDate not supplied

Effect of posture in immediate post-exercise period on ischaemic ST-changes during stress electrocardiographic testing.

In this study of stress testing, the posture in which patients were put had effect on heart rate, blood pressure, rate pressure product and ST-segment depression integral in the recovery phase. The systolic blood pressure in recovery phase of stress testing fell more rapidly towards normal pre-exercise value in sitting (Group I) than in lying down (Group II) posture (p < 0.05) from 2nd to 5th minute. The changes in heart rate were less and slower in lying posture than with sitting up. The decrease in rate pressure product (RPP), a determinant of myocardial oxygen requirement was lower in lying down than in sitting up posture (p < 0.05) from 2nd to 5th minute of recovery. Consequently, ST-depression, a marker of ischaemia was more marked in lying down than sitting up. The ST-depression integral was 4.15 +/- 1.2 and 7.10 +/- 1.65 in 2nd minute in group I and group II respectively, and the difference was statistically significant in 2nd, 7th (p < 0.05) and 8th minute (p < 0.01) of recovery. These changes are important in interpretation of results of exercise testing.

Coronary Disease↗
PubMed2006

[Dynamic characteristics of SARA during liver fibrogenesis in rats].

OBJECTIVES: To investigate the dynamic characteristics of Smad anchor for receptor activation (SARA) expression during liver fibrogenesis in rats and the relationship between SARA and liver fibrosis. METHODS: Liver fibrosis was induced in 74 rats by intraperitoneal injection of dimethylnitrosamine (DMN) with a dosage of 10 microl/kg body weight, once a day, 3 days per week for 4 weeks. The model rats were randomly divided into 9 groups for studying the changes: 1 d, 3 ds, 1 week, 2 weeks, 3 weeks and 4 weeks after starting the ip injections (intoxicating phase), and 1 week, 2 weeks and 4 weeks after stopping the injections (5th w, 7th w and 8th w, recovery phase). Each group included 5 to 8 rats. In addition, 10 non-treated rats served as normal controls. The rat liver tissues were examined. Collagen deposition was stained with Sirius red, and hydroxyproline (Hyp) was measured with Jamall' method. SARA spatial expression in the livers was detected by immunohistochemistry, and the expressions of TGFbeta1, alpha-SMA and SARA protein were detected by Western blot. The relationships of SARA with Hyp, TGFbeta1 and alpha-SMA were analyzed. RESULTS: During the intoxicating phase, the rat hepatic collagen production (Hyp content) and deposition increased as DMN intoxication continued, and there was marked fibrous septum and pseudo-lobule formation at the end of the 4th w. During the recovery phase, the rat hepatic collagen deposition and fibrous septum formation were lessened, but the Hyp content in the livers of the model rats at the end of 4th w, 5th w, 6th w and 8th w was still higher than that of the controls (193.04+/-39.15, 188.49+/-39.92, 174.39+/-21.22, 163.59+/-31.47 vs 125.64+/-19.51; t from 3.43 to 4.9, P<0.01). SARA was mainly stained positively in interstitial cells surrounding the hepatic sinusoids in both normal and fibrotic livers, and the number of the positive stained cells decreased as liver fibrosis developed, and gradually returned to normal after stopping the intoxication. The expressions of TGFbeta1 and alpha-SMA were gradually increased, as shown with Western blot, but SARA decreased as liver fibrosis developed. The expressions of TGFbeta1 and alpha-SMA were slightly decreased, SARA expression recovered to the normal level after stopping the DMN intoxication. During liver fibrosis developing and recovery phases, SARA was significantly negatively correlated with TGFbeta1 and alpha-SMA expressions and Hyp contents. CONCLUSIONS: SARA was mainly expressed in the liver interstitial cells, and it was negatively correlated with liver fibrosis formation.

Actins↗
PubMed1996

Renal wedge-shaped lesions on computed tomography and ultrasonography in two patients who developed acute renal failure with severe loin pain after exercise.

Acute renal failure (ARF) with loin pain after exercise with development of wedge-shaped contrast enhancement on computed tomography (CT) has been described as a new disease entity. We report 2 patients who developed ARF with severe loin pain after exercise, showing wedge-shaped lesions both on CT and ultrasonography. Renal ultrasonography showed indistinct wedge-shaped lesions when performed at oliguric or recovery phase of ARF, whereas it showed distinct lesions when done between these two phases. Contrast CT performed at the recovery phase disclosed distinct wedge-shaped lesions. Our findings suggested that the best time to detect these lesions by ultrasonography is between at the beginning of diuresis and at the time of serum creatinine levels of 2 mg/dl.

Acute Kidney Injury↗
PubMed2004

Expression of osteopontin in cisplatin-induced tubular injury.

Osteopontin (OPN) is considered as a key protein in cell regeneration. OPN is thought to have many functions in cell-cell binding and cell-matrix binding via OPN receptors in various organs. But there is little information on the precise role of OPN. To clarify the functional role of OPN in tubular injury, we performed in situ hybridization and immunohistochemical analysis of the expression of OPN in a renal cortical necrosis model induced by cisplatin from the acute injury to late recovery phases. In the acute injury phase, both mRNA and protein of OPN were markedly induced in damaged tubular lumens with cell debris. In the late recovery phase, on the other hand, OPN protein and mRNA were observed in dilated and flattened tubular epithelial cells showing a regenerative appearance. Most of these cells were also immunostained with CD44, a receptor of OPN. PCNA staining was also co-localized with these expressions. In light of the CD44 function regulating cell proliferation, these findings suggest that OPN may contribute to regeneration of tubular epithelial cells during the acute to late recovery phases of cortical tubular damage induced by cisplatin.

Animals↗
PubMed2004

Secondary energy failure after cerebral hypoxia-ischemia in the immature rat.

A delayed or secondary energy failure occurs during recovery from perinatal cerebral hypoxia-ischemia. The question remains as to whether the energy failure causes or accentuates the ultimate brain damage or is a consequence of cell death. To resolve the issue, 7-day postnatal rats underwent unilateral common carotid artery occlusion followed thereafter by systemic hypoxia with 8% oxygen for 2.5 hours. During recovery, the brains were quick frozen and individually processed for histology and the measurements of 1) high-energy phosphate reserves and 2) neuronal (MAP-2, SNAP-25) and glial (GFAP) proteins. Phosphocreatine (PCr) and ATP, initially depleted during hypoxia-ischemia, were partially restored during the first 18 hours of recovery, with secondary depletions at 24 and 48 hours. During the initial recovery phase (6 to 18 hours), there was a significant correlation between PCr and the histology score (0 to 3), but not for ATP. During the late recovery phase, there was a highly significant correlation between all measured metabolites and the damage score. Significant correlation also exhibited between the neuronal protein markers, MAP-2 and SNAP-25, and PCr as well as the sum of PCr and Cr at both phases of recovery. No correlation existed between the high-energy reserves and the glial protein marker, GFAP. The close correspondence of PCr to histologic brain damage and the loss of MAP-2 and SNAP-25 during both the early and late recovery intervals suggest evolving cellular destruction as the primary event, which precedes and leads to the secondary energy failure.

Adenosine Triphosphate↗
PubMed1990

Mechanical restitution in isolated mammalian myocardium: species differences and underlying mechanisms.

Ventricular myocardium was obtained from guinea-pig, ferret and human hearts. In each case small strips were mounted isometrically in a tissue bath and superfused with a physiological saline at 37 degrees C. The preparations were stimulated at 1 Hz and ectopic stimuli of different preceding intervals were given. The relationship between the force produced by the ectopic contraction and the duration of the preceding interval was plotted to form mechanical restitution curves (MRC). In the guinea-pig the MRC is described by a rapid recovery phase with an exponential time constant of 220 +/- 22.7 ms (mean +/- S.E.M.) followed by a decay (28.5 +/- 8.4 s). In ferret and man the rising phase is described by two exponentials (192.5 +/- 43.2 ms and 4.4 +/- 1.5 s in the ferret; 259.7 +/- 45.2 ms and 3.0 +/- 1.0 s in man). The decay phase is slower in ferret (22 +/- 156 s, P less than 0.02) and man (177 +/- 70 s, P less than 0.002) than in guinea-pig. There was no significant difference between the time constants of the rapid recovery phase of mechanical restitution in each species. The time constant of the rapid recovery phase (tau 1) was abbreviated by ryanodine, ouabain and adrenaline in human myocardium and by ryanodine alone in guinea-pig. Verapamil increased tau 1 in both species. The decay time constant (tau 3) was prolonged by ouabain, verapamil and by increasing extracellular [Ca2+] in human myocardium and by ouabain and verapamil in guinea-pig. The recovery of the second inward current in human myocardium was not correlated to the recovery of mechanical function. It is suggested that tau 1 is dependent on the recycling of Ca2+ within the cell as well as the reactivation of the second inward current. The decay phase, tau 3, is dependent on the rate of Ca2+ efflux from the cell, possibly via a Na+/Ca2+ exchange mechanism. The mechanisms underlying the slow recovery time constant, tau 2, are unclear but it is important to calculate tau 2 for the proper evaluation of tau 1.

Animals↗