Functional gastrointestinal disorders

Abdominal massage: A review of clinical and experimental studies from 1990 to 2021

OBJECTIVE

To systematically review the current state and holistic application of abdominal massage (AM).

DESIGN

A systematic review of qualitative evidence was conducted. All English articles exploring the topic of AM that had been published until the end of June 2021 were retrieved.

DATA SOURCES

The PubMed, Cochrane library, and Embase databases were accessed. Some original texts were obtained from Google Scholar.

DATA EXTRACTION AND SYNTHESIS

Two authors independently evaluated all search data to identify relevant studies. Disagreements were settled by discussion with a third author. Results were independently extracted into standardized sheets and checked for accuracy.

MAIN RESULTS

A total of 107 full-text reports were eligible for inclusion. Adult digestive disorders, pediatric disorders, gynecological disorders, obstetric disorders, metabolic disorders, psychological disorders, the side effects of AM, and animal experiments accounted for 49.53%, 14.02%, 7.48%, 7.48%, 4.67%, 4.67%, 5.61%, and 6.54% of all these papers, respectively, with most reports focusing on clinical studies.

CONCLUSION

The variety of diseases treated with AM is gradually increasing, and the treatment programs of AM for many diseases are being gradually optimized. Different forms of AM, especially mechanical AM, have been widely studied; the side effects of AM have also been considered; and the possible mechanisms of AM therapy continue to be discovered. In general, AM is an effective and safe therapy and can be widely used in various diseases, but further studies are necessary to clarify the mechanism of AM for different diseases. In the future, AM could become an even safer, more popular, and more modern therapy.

Development of a new method for small bowel transit study

BACKGROUND AND PURPOSE

Currently, most studies combine the small bowel transit examination with gastric emptying time examination. There are significant drawbacks to this method. The radiotracer does not enter the small intestine in a bolus and the starting time for transit in the duodenum is difficult to define. This makes the result unreliable. In this study, we used a commercial enteric capsule containing radioactive charcoal to solve these problems.

MATERIALS AND METHODS

Activated charcoal powder was mixed with Tc-99m pertechnetate and loaded to the enteric capsule which can resist gastric acid and dissolve only in the small intestine. In-vitro stability experiment was performed by immersing these capsules in a colorless phosphate buffer of variable pH which mimicked the condition in stomach and small intestine. In addition, ten healthy Chinese volunteers were included for in-vivo experiment. Anterior and posterior views of abdomen were obtained at regular 30-minute intervals until the eighth hour after administration of the radioactive enteric capsule. Small bowel transit time was calculated.

RESULTS

The enteric capsule remained intact for at least 480 minutes in the solution mimicking gastric content (pH = 3.0) and disrupted at a mean duration of 227.2 minutes at a pH of 6.8 and at a mean duration of 212.4 minutes at a pH of 7.4 in the solution mimicking pancreaticobiliary secretions. In nine of ten volunteers, the small bowel transit time was between 30 to 270 minutes with a mean transit time of 140 min. In one volunteer, we failed to detect the exact time of small bowel transit because the capsule remained in the stomach throughout the study for up to 8 hours.

CONCLUSIONS

We consider activated charcoal labeled with Tc-99m pertechnetate using an enteric capsule as the carrier to be a potential radioactive marker for small bowel transit study.

Illness perceptions in people with acute bacterial gastro-enteritis

Functional gastro-intestinal disorders (FGID) like irritable bowel syndrome (IBS) are common and can develop after gastro-enteritis. Illness representations may be important influences on the development of post-infectious FGIDs. Here, we studied both the relationship between prior chronic symptoms (FGIDs) and illness perception during an acute illness (bacterial gastro-enteritis) as well as the relationship between illness perception during an acute illness (bacterial gastro-enteritis) and the subsequent development of chronic abdominal symptoms. Two hundred and seventeen people with recent gastro-enteritis completed a questionnaire asking about gut symptoms consistent with a diagnosis of IBS, functional dyspepsia or functional diarrhoea and the Illness Perception Questionnaire. Those without a prior FGID were followed up and completed a similar gut questionnaire at six months. People with a prior FGID had significantly more symptoms and scored significantly higher on the timeline and consequence scores than those without. People who developed a FGID had a non-significantly higher number of symptoms and higher consequence and timeline scores than those who did not. Neither comparative group differed in the control/cure scores or causation scores. The implications of the findings are discussed.

Role of nuclear medicine in evaluating patients with suspected gastrointestinal motility disorders

Functional symptoms caused by gastrointestinal motility disorders are relatively common in the general population. Knowledge of the relationship between symptoms and the underlying gastrointestinal dysmotility provides physicians with a framework for successful evaluation and treatment of patients with possible motor disorders of the gastrointestinal tract. Scintigraphy provides for noninvasive and quantitative assessment of physiological transit throughout the gastrointestinal tract, and it is extremely useful for diagnosing gastrointestinal motor dysfunction. The wide range of scintigraphic studies now available supplement other diagnostic tests for evaluation of all segments of the gastrointestinal tract.

Irritable bowel syndrome. Managing the patient with abdominal pain and altered bowel habits

Irritable bowel syndrome is a common complex of syndromes thought to be generated by a motility or sensory disturbance of the gastrointestinal tract. It is a frequent cause of chronic abdominal pain and altered bowel habits. Patients who seek medical attention for irritable bowel syndrome often do so because of psychosocial factors. Therapy remains largely empirical, directed toward the relief of symptoms in the context of a supportive physician-patient relationship.

Reversal of gastric electrical dysrhythmias by cisapride in children with functional dyspepsia. Report of three cases

Three children (ages 5, 7.6, and 8 years), with recurrent unexplained upper abdominal symptoms such as vomiting, epigastric pain, anorexia, early satiety and without structural or mucosal abnormalities of gastrointestinal tract, underwent electrogastrography (EGG)--recording of gastric electrical activity using cutaneous electrodes positioned on the epigastric region and connected to a recording polygraph. Frequency of EGG signals was analyzed by fast Fourier transform. Significant changes of fasting and fed gastric myoelectrical activity (tachygastria, bradygastria, flatline pattern) were recorded in the three patients; furthermore, gastric emptying (GE) of a solid-liquid mixed meal, measured by ultrasonography, was significantly prolonged in them. A follow-up study was carried out after an eight-week course with oral cisapride: in all patients symptoms improved, GE time normalized, and EGG analysis showed normal electrical rhythm. It is suggested that gastric dysrhythmias can play a pathogenetic role in patients with functional gastrointestinal symptoms and that symptomatic improvement is accompanied by normalization of gastric electrical rhythm.

Towards a relatively inexpensive, noninvasive, accurate test for colonic motility disorders

Currently available clinical tests of colonic transit, such as the radiopaque marker method, are useful to detect delayed transit but may be less sensitive for rapid transit. The aim of this study was to develop a relatively inexpensive, noninvasive, accurate test of colonic transit using selected scintigraphic observations within the first 24 hours after ingestion of a pH-sensitive, methacrylate-coated, delayed-release capsule containing 111In-labeled resin pellets. The authors' previously published colonic transit data on 22 healthy subjects, 9 patients with diarrhea-predominant irritable bowel syndrome, and 7 patients with idiopathic constipation and previously unpublished data on 4 patients with carcinoid diarrhea were analyzed. A logistic discriminant analysis was used to estimate the sensitivity and specificity of selected combinations or simple summaries of transit. Among combined transit summaries, the emptying rate of the proximal colon was significantly different between healthy and constipation groups; the geometric center of isotope in the colon at 4 hours was significantly greater in the diarrhea group than in healthy controls; the geometric center at 24 hours was significantly lower in the constipation group than in the other two groups. From the logistic discriminant analysis, simple summaries of transit also had significant discriminant value; these included the isotopic contents in the ascending, transverse, and descending colon at 4 hours and the counts in the ascending and transverse colon and stool at 24 hours. At 90% sensitivity, the specificity of the transverse colon counts at 4 hours was 79%, which is identical to the specificity of the proximal colon emptying rate, both adjusted for age. Thus, quantitation of isotopic counts in colonic regions on scans taken at 4 and 24 hours provides an accurate summary of colonic transit, with acceptable specificity at a high sensitivity in the detection of motility disorders of the colon.

Abnormalities of gastrointestinal motility in children with nonulcer dyspepsia and in children with gastroesophageal reflux disease

In 11 children (mean age 44.2 months) with symptoms suggesting upper intestinal dysfunction (nonulcer dyspepsia), in nine children (mean age 27.3 months) with gastroesophageal reflux (GER) disease, and in seven controls (mean age 20.4 months) we investigated fasting [for 3 hr or until two migrating motor complexes (MMC) were observed] and fed (90 min) antroduodenal motility by means of perfused catheter system; furthermore, we measured both gastric emptying of a radiolabeled milk formula and fasting duodenogastric reflux during manometry by assessing bile salt concentration in gastric aspirates. No structural abnormalities of gastrointestinal tract and organic disorders were detected in the patients. In a high proportion of both groups of patients we found manometric abnormalities of interdigestive and fed motor patterns that were not seen in the controls: absence of antral phase III of MMC; significant decrease of antral and/or duodenal motor activity during fasting and/or fed periods; abnormal propagation or configuration of MMC phase III that was significantly shorter than in controls; bursts of sustained fasting and/or fed phasic duodenal activity, frequently uncoordinated with adjacent gut segments. When compared to controls, the mean intragastric concentration of bile salts during all MMC phases and the mean 1-hr percent gastric activity of the radiolabeled milk were significantly higher in the two groups of patients. We conclude that in a high proportion of children with nonulcer dyspepsia and of children with GER disease, gastrointestinal manometry may reveal significant irregularities of antral and duodenal motility, which are associated with increased duodenogastric reflux and delayed gastric emptying.

Towards a less costly but accurate test of gastric emptying and small bowel transit

Our aim is to develop a less costly but accurate test of stomach emptying and small bowel transit by utilizing selected scintigraphic observations 1-6 hr after ingestion of a radiolabeled solid meal. These selected data were compared with more detailed analyses that require multiple scans and labor-intensive technical support. A logistic discriminant analysis was used to estimate the sensitivity and specificity of selected summaries of scintigraphic transit measurements. We studied 14 patients with motility disorders (eight neuropathic and six myopathic, confirmed by standard gastrointestinal manometry) and 37 healthy subjects. The patient group had abnormal gastric emptying (GE) and small bowel transit time (SBTT). The proportion of radiolabel retained in the stomach from 2 to 4 hr (GE 2 hr, GE 3 hr, GE 4 hr), as well as the proportion filling the colon at 4 and 6 hr (CF 4 hr, CF 6 hr) were individually able to differentiate health from disease (P less than 0.05 for each). From the logistic discriminant model, an estimated sensitivity of 93% resulted in similar specificities for detailed and selected transit parameters for gastric emptying (range: 62-70%). Similarly, combining selected observations, such as GE 4 hr with CF 6 hr, had a specificity of 76%, which was similar to the specificity of combinations of more detailed analyses. Based on the present studies and future confirmation in a larger number of patients, including those with less severe motility disorders, the 2-, 4-, and 6-hr scans with quantitation of proportions of counts in stomach and colon should provide a useful, relatively inexpensive strategy to identify and monitor motility disorders in clinical and epidemiologic studies.

Non-ulcer dyspepsia

This paper discusses the definition of non-ulcer dyspepsia and its relationship to other functional bowel disorders. The research on the prevalence, outcome, aetiology and management of this condition is reviewed with particular emphasis on its multifactorial nature. Future research will need to concentrate on the inter-relationship of physical and psychosocial factors including the health beliefs of the individual patient.

Disorders of gastrointestinal motility in neurologic diseases

Neurologic diseases can affect the bowel at several levels of innervation--by altering the electrical activity that controls smooth muscle, the enteric nervous system, or the extrinsic neural pathways to the gut. This review concentrates on disorders of motility that occur in conjunction with diseases of the extrinsic neural supply (from the level of the brain to the postganglionic fibers) and those generalized disorders that affect gut smooth muscle. Modern technology, such as gastrointestinal scintigraphy and manometric techniques that measure esophageal, gastroduodenal, and anorectal motility (intraluminal pressures), has provided better methods to study the pathophysiologic aspects of gut motility in diseases of the nervous system. Distinguishing the neuropathies of the extrinsic nervous system from those of the intrinsic (enteric) nervous system is not always possible because the available techniques evaluate only the end-organ--that is, the motor function of the gut. Degenerative or infiltrative (myopathic) disorders of gut smooth muscle, however, can be distinguished from such neuropathies, and careful and systematic evaluation of autonomic function can often identify the level of disordered function in the neural-gut axis.

Idiopathic autonomic denervation in eight patients presenting with functional gastrointestinal disease. A causal association?

Gut dysmotility may result from disease of the extrinsic neural pathways supplying the gut. We report the results of studies on sweating, cardiovascular, and sudomotor reflexes in eight prospectively evaluated patients with apparently functional gastrointestinal disorders. There was no personal or family history of neurologic disease, except for one patient with known atony of the bladder. Motility of the esophagus, stomach, and small intestine were, respectively, abnormal in two, six, and seven patients and showed either uncoordination of contractions between segments or postcibal hypomotility. All had generalized or patchy anhidrosis; quantitative sudomotor axon reflex tests were also abnormal in four patients and borderline in one. Plasma levels of catecholamines were abnormal in one patient. All patients had evidence of sympathetic denervation: preganglionic in two patients, postganglionic in five patients, and mixed in one patient. Three patients also had abnormal heart-rate responses to deep breathing, suggesting parasympathetic dysfunction. No underlying cause for the autonomic dysfunction was identified in any of these patients despite extensive investigations. Thus, these data support the hypothesis that apparently functional gastrointestinal disorders may be due to idiopathic autonomic denervation.

Motility disorders and stress

The association between emotion and gastrointestinal dysfunction has been postulated for centuries, and all practicing clinicians have anecdotal experience of the association between stress and irritable bowel syndrome (IBS). However, definite proof of an etiologic link between stress and gut motor dysfunction remains elusive, despite the large number of publications on this topic. A critical appraisal of methodology, use of controls, data interpretation, and significance of findings in the published literature is necessary to assess the present state of knowledge and to develop more meaningful studies in the future. This review attempts to summarize these perspectives.

Leanness, peptide hormones and premenopausal breast cancer

Environmental factors promote the development of and decrease survival from Breast Cancer. Prospective morphological and hormonal studies indicate biological markers for this disease are evident in premenopausal women. The majority of premenopausal patients are non-obese (Body Mass Index, BMI less than 25). Lean women have a greater proportion of estrogen receptor negative (ER-) tumours, which may grow faster and have a higher concentration of epithelial growth factor (EGF). We have reported that lean, BMI less than 23, versus obese, BMI greater than 28, women have a different gut-pancreatic peptide hormone response to meals and that differences in these peptide hormones occur between healthy and age weight matched premenopausal patients. We hypothesize that the diet peptide hormone control of food intake in lean women is associated with the development of mammary dysplasia, change in growth factor profile and steroid hormone metabolism.

Circadian rhythms in patients with abdominal pain syndromes

Circadian rhythms for cortisol, 6-sulphatoxy melatonin and core body temperature were compared in control subjects and patients with functional abdominal pain. There were 20 patients with biliary pain after cholecystectomy, ten with biliary pain without cholecystectomy and 14 with irritable bowel syndrome. Rhythms were determined by urine collections at intervals of 4 h for 48 h and by overnight monitoring of core body temperature using the Vitalog system. Data were fitted to a sine curve to yield the time of maximal urinary excretion/lowest temperature and the amplitude of each rhythm. Urinary excretion of free cortisol was similar in patients and control subjects. For urinary 6-sulphatoxy melatonin, the timing (phase) of rhythms was similar in patients and controls but those with pain had a lower urinary excretion of 6-sulphatoxy melatonin (p less than 0.05) and a rhythm of lower amplitude (p less than 0.02). The amplitude of the temperature rhythm was also lower in patients with biliary pain with and without prior cholecystectomy (p less than 0.05). Functional abdominal pain is associated with 6-sulphatoxy melatonin and temperature rhythms of low amplitude, presumably because of suppression of circadian oscillators.

Food intolerance in duodenal ulcer patients, non ulcer dyspeptic patients and healthy subjects. A prospective study

In 50 duodenal ulcer out-patients and 50 non ulcer dyspeptic patients suffering from low to moderate epigastric painful symptoms the intolerance of 39 foods were significantly increased compared to a group of 50 healthy subjects. Food intolerance was not different between duodenal ulcer and non ulcer dyspeptic patients. Intolerance was related in the majority of nutrients to aversion and pain or to an increased incidence of aversion alone in patients and normals. In duodenal ulcer, coffee and fruit juice were associated with an elevated incidence of pain.

Psychologic aspects of flatulent dyspepsia

Psychologic and social factors have been implicated in the aetiology of dyspepsia. In this study these factors were investigated in relation to flatulent dyspepsia, a symptom complex that has traditionally been associated with gallbladder disease. Subjects completed the Middlesex Hospital Questionnaire and the Life Events Inventory and were interviewed in detail, using a semi-structured format. Three groups of patients with flatulent dyspepsia--those with and without gallbladder disease and post-cholecystectomy--all had significantly more associated somatic symptoms than non-dyspeptic subjects with gallbladder disease or normal controls, thus indicating greater emotional upset amongst dyspeptic patients. There was little evidence that symptoms were related to stressful life events.

Diagnosing psychiatric disorders in adolescent females with abdominal pain

Psychiatric diseases, recently renamed psychiatric disorders by the American Psychiatric Association, are commonly associated with abdominal pain in adolescents but may be difficult to diagnose. In a prospective study, we evaluated four psychiatric scales, including the Childhood Depression Inventory (CDI) and the Speilberger State-Trait Anxiety Inventory (STAI) as aids in the diagnosis of psychiatric disorders in 40 adolescent females with abdominal pain. Final diagnosis of organic-dysfunctional disease was made in 32 patients, and a psychiatric disorder was found in eight. Only the CDI (p = 0.001) and the State (p = 0.006) and Trait (p = 0.022) scales of the STAI had significantly different mean values between subjects with organic-dysfunctional disease and a psychiatric disorder. Almost all subjects with a psychiatric disorder had abnormally high scores, whereas the subjects with organic-dysfunctional disease did not. We conclude that three brief, self-administered psychiatric scales may be useful in differentiating between organic-dysfunctional disease and a psychiatric disorder in adolescent patients with abdominal pain.

Society, brain and gut--a psychosocial approach to dyspepsia

Common denominators in the etiology of psychosocially induced ill health--in the gastrointestinal tract and elsewhere--flow from discrepancies between human ability, needs, and expectations on the one hand, and environmental demands, opportunities, and individual perception of these on the other. Pathogenic mechanisms include emotional reactions (anxiety, depression, hypochondria), behavioural reactions (abuse of alcohol, drugs, and tobacco, destructive and self-destructive behaviour, and resistance to prevention, therapy and rehabilitation), and physiological reactions (neuroendocrine and immunological). Through these mechanisms, psychosocial stressors can precipitate ill health, influence well-being, and modify the outcome of health action. Interacting variables (coping, social support) can buffer these effects. One of the targets of such influences is the gastrointestinal tract. Present knowledge concerning socio-psycho-gastrointestinal interrelationships is far from conclusive. Some of its implications for therapeutic approaches to gastrointestinal patients are discussed.

Gastric and autonomic responses to stress in functional dyspepsia

It has been suggested that functional dyspepsia might arise from the effect of stress on upper gut motility in susceptible individuals. The aim of this study was to evaluate posticibal antral motility in the presence and absence of sustained experimental stress by means of a transcutaneous electrical nerve stimulator. Two groups of patients could be recognized from these studies: first, those with postcibal antral hypomotility that was not changed during stress; and second, patients with normal postcibal motility which was normally suppressed by stress. Experimental stress significantly increased skin conductance and plasma beta-endorphin levels. However, in these two groups, there were no differences in clinical presentation and personality traits or in autonomic and humoral variables either before or during stress. Stepwise discriminant analysis of the autonomic or humoral responses to stress was unable to predict the different postcibal antral motor responses among the subsets of patients with functional dyspepsia. These data suggest that there are two subtypes of antral motility in functional dyspepsia: disordered gastric function under basal conditions resulting in antral hypomotility, and normal basal antral motility and autonomic and gastric motor responses to stress. In the latter subgroup, the cause of symptoms is unclear, but it appears not to be a motility disorder.

Dermatoglyphic (fingerprint) evidence for a congenital syndrome of early onset constipation and abdominal pain

Chronic idiopathic constipation and abdominal pain are the most common gastrointestinal symptoms but their cause is rarely determined; therefore, they usually are called functional. To determine if congenital factors play a role in these disorders, we examined dermatoglyphic (fingerprint) patterns, a congenital marker, in 155 consecutive patients with gastrointestinal complaints. Sixty-four percent of patients with constipation and abdominal pain before age 10 yr had one or more digital arches, compared with 10% of patients without constipation and abdominal pain (p less than 0.001). Seventy percent of constipated patients with arches had the onset of symptoms before age 10 yr compared with 23% of constipated patients without arches (p less than 0.001) and 14% of patients with symptoms other than constipation (p less than 0.001). Compared with an age- and sex-matched sample of patients without arches, patients with arches had a higher prevalence of constipation and abdominal pain before age 10 (p = 0.003), were more likely (p less than 0.001) to have chronic intestinal pseudoobstruction (an organic disorder), and were less likely (p = 0.013) to have irritable bowel syndrome (a functional disorder). Identification of a congenital marker, digital arches, associated with early onset constipation and abdominal pain may help to differentiate a congenital organic syndrome from functional disorders such as the irritable bowel syndrome.

Techniques in evacuation proctography in the diagnosis of intractable constipation and related disorders

A technique of evacuation proctography using a simple barium and air mixture is described. The study can be easily combined with a barium enema examination. A series of 35 patients with intractable constipation have been studied and compared with 7 controls. Most of the abnormalities seen using more elaborate methods of defaecography were identified. Variants of rectal intussusception were found in 16 patients. Other diagnoses included rectocele, mucosal and full rectal prolapse, accentuation of puborectalis impression and solitary rectal ulcer. The technique should prove useful in the management of patients with disorders of defaecation.

Abnormal duodenal loop in patients with irritable bowel syndrome

The frequency of an abnormal duodenal loop (AD) was investigated in 36 patients with irritable bowel syndrome (IBS) and in a sex- and age-matched control group of patients with Crohn's disease. The frequency was significantly higher in the patients with IBS than in the control group (41% versus 18%; p less than 0.02). Among IBS patients with AD, the frequency of food-provoked pain was higher than in IBS patients with a normal duodenum (65% versus 21%; p less than 0.01). We conclude that AD may be one of the reasons for complaints in IBS.

Evacuation proctography in obstructed defaecation and rectal intussusception

The symptoms of obstructed defaecation may present as a number of different syndromes including descending perineum, solitary rectal ulcer, irritable bowel and mucosal or complete rectal prolapse. In order to clarify the pathophysiology of obstructed defaecation we carried out dynamic and static radiological investigations together with manometric and electrophysiological measurements in ten patients with severe, intractable obstructed defaecation. Results were compared with a total of 35 control subjects. There were no significant differences in sphincter pressures or the recto-anal inhibitory reflex between patients and controls. Mean motor unit potential duration was prolonged in patients compared with controls (P less than 0.02) in the puborectalis and external sphincter indicative of neuropathic changes. X-ray measurements of the anorectal angle and perineal descent at rest showed no differences. However, obstructed defaecation patients had a greater increase in anorectal angle on straining (P less than 0.02) and significantly more descent on straining (P less than 0.002). Fast film sequence evacuation proctography showed that the anal canal was occluded by anterior rectal wall in four patients and five patients had variants of recto-rectal intussusception without overt rectal prolapse, which explained the obstructive symptoms. This information should allow the surgeon to follow a rational treatment programme based on the anatomical abnormality.

[Eicosanoids and phospholipases]

Prostaglandins, thromboxanes, and leukotrienes have been implicated to play an important role in physiology as well as in a growing list of pathophysiologic conditions. These oxidation products of 8.11.14-eicosatrienoic-, 5.8.11.14.-eicosatetraenoic-, and 5.8.11.14.17.-pentaenoic acids have been collectively designated eicosanoids. Many clinically important diseases are associated with altered eicosanoid biosynthesis. Furthermore, a series of hormones are known to induce acutely formation of eicosanoids, suggesting a crucial role in a multitude of tissue responses including phenomena such as secretion, platelet aggregation, chemotaxis, and smooth muscle contraction. The major precursor for the eicosanoids seems to be 5.8.11.14.-eicosatetraenoic acid or arachidonic acid. Virtually all of arachidonic acid however is present in esterified form in complex glycerolipids. Since cyclooxygenase and the lipoxygenases utilize arachidonic acid in its free form, a set of acylhydrolases is required to liberate arachidonic acid from membrane lipids before eicosanoid formation can occur. It became only recently apparent that a minor acidic phospholipid, phosphatidylinositol, comprising only 5%-10% of the phospholipid mass in mammalian cells, plays an important role in arachidonic acid metabolism. Phosphatidylinositol--after phosphorylation to phosphatidylinositolphosphate and phosphatidylinositolbisphosphate--appears to be hydrolyzed by specific phospholipases C generating 1-stearoyl-2-arachidonoyl-diglyceride. Diglyceride serves as substrate for diglyceride lipase to form monoglyceride and free fatty acid. Alternatively diglyceride is phosphorylated by diglyceride kinase yielding phosphatidic acid, which is believed to be reincorporated into phosphatidylinositol. In addition to phosphatidylinositol phosphatidylcholine, phosphatidylethanolamine and phosphatidic acid may contribute to arachidonic acid release. These phospholipids are substrates for phospholipases A2 generating free arachidonic acid and the respective lysophospholipid. Understanding of the biochemistry of arachidonic acid liberation may be critical in developing strategies of pharmacological intervention in a variety of pathological conditions.