Pharmacokinetic study of ellagic acid in rat after oral administration of pomegranate leaf extract

Quantification of ellagic acid, the principal bioactive component of pomegranate leaf extract, in rats plasma following oral administration of pomegranate leaf extract was achieved by using a high-performance liquid chromatographic method. The calibration curve for ellagic acid was linear (r2=0.9998) ver the concentration range 0.026-1.3 microg/ml. The intra- and inter-day assays of ellagic acid from rat plasma were less than 6.52% at concentration range from 26 to 1300 ng/ml and good overall recoveries (94.5-102.4%) were found on same concentrations. The concentration-time profile was fitted with an open two-compartment system with lag time and its max concentration of ellagic acid in plasma was 213 ng/ml only 0.55 h after oral administration extract 0.8 g/kg. The pharmacokinetic profile indicates that ellagic acid has poor absorption and rapid elimination after oral administration pomegranate leaf extract, and part of it was absorbed from stomach.     

Thrombin-induced alterations in lung fluid balance in awake sheep

We examined the effect of fibrinolysis depression on thrombin-induced pulmonary microembolism in awake sheep prepared with chronic lung lymph fistulas. Fibrinolysis was depressed by an intravenous infusion (100 mg) of tranexamic acid [trans-4-(Aminomethyl)cyclohexanecarboxylic acid]. Pulmonary microembolism was induced by an intravenous infusion of alpha-thrombin (80 NIH U/kg) in normal (n = 7) and in tranexamic acid-treated (n = 6) sheep. Thrombin immediately increased pulmonary lymph flow (Qlym) in both groups. The increased Qlym was not associated with a change in the lymph-to-plasma protein concentration (L/P) ratio in the control group and with a small decrease in the tranexamic acid-treated group. The increases in Qlym and pulmonary transvascular protein clearance (Qlym X L/P ratio) in the tranexamic acid-treated group were greater and sustained at four- to fivefold above base line for 10 h after the thrombin and remained elevated at twofold above base line even at 24 h. In contrast, Qlym and protein clearance were transiently increased in the control group. The mean pulmonary arterial pressure (Ppa) and pulmonary vascular resistance (PVR) increased after thrombin in tranexamic acid-treated group; the increases in Ppa and PVR in the control group were transient. Protein reflection coefficient as determined by the filtration independent method decreased after thrombin in tranexamic acid-treated sheep (n = 5), indicating an increased vascular permeability to proteins. We conclude that prolongation of microthrombi retention in the pulmonary circulation results in an increased vascular permeability to proteins. Both increased vascular permeability and vascular hydrostatic pressure are important determinants of the increases in Qlym and transvascular protein clearance after thrombin-induced pulmonary microembolism.     

Tranexamic Acid in Control of Haemorrhage after Dental Extraction in Haemophilia and Christmas Disease

In a double-blind trial tranexamic acid (AMCA, Cyclokapron), 1 g three times a day for five days, significantly reduced blood loss and transfusion requirements after dental extraction in patients with haemophilia and Christmas disease. No side effects were seen in either group of patients. Screening tests showed no toxic action of tranexamic acid on the liver, kidney, or heart.     

Pulmonary responses to tracheal or esophageal acidification in guinea pigs with airway inflammation.

The association between asthma and gastroesophageal reflux has been attributed to microaspiration of gastric contents and/or vagally mediated reflex bronchoconstriction. In previous experimental studies concerning the pulmonary effects of tracheal or esophageal acid infusion, only animals without airway inflammation have been studied. We assessed the effects of esophageal and tracheal administration of hydrochloric acid (HCl) on normal guinea pigs (GP) and GP with airway inflammation induced by repeated ovalbumin exposures. These GP were anesthetized (pentobarbital sodium) and received 1) 20 microl of either 0.2 N HCl or saline into the trachea, or 2) 1 ml of either 1 N HCl or saline into the esophagus. Intratracheal HCl resulted in a significant increase in both respiratory system elastance and resistance (P < 0.001). There were no significant changes in respiratory mechanics when HCl was infused into the esophagus. In conclusion, we observed that infusion of large volumes of HCl into the esophagus did not change pulmonary mechanics significantly, even in guinea pigs with chronic allergen-induced airway inflammation. In contrast, intratracheal administration of small amounts of acid had substantial effects in normal GP and GP with airway inflammation.     

Neuronal transmission of hippocampal CA1 neurones is modulated by corticotropin-like intermediate lobe peptide [CLIP; ACTH(18–39)]

The study was conducted to test whether CLIP [ACTH(18–39)] influences the neuronal transmission and the induction of longterm potentiation (LTP) in the hippocampus. The population spike was recorded in the hippocampal CA1 region of freely moving rats before and after intracerebroventricular (ICV) administration of CLIP in comparison to ACTH and saline (controls). After infusion of CLIP, the population spike amplitude (PSA) rose to about 200% of baseline values. After reaching this level, it was impossible to induce a further increase of PSA by tetanization. However, if the stimulus intensity was reduced to a new baseline level, electrically induced LTP could be observed. There were no significant changes after infusion of ACTH. Our results indicate that the ICV administration of CLIP leads to an enhancement of excitability in the hippocampal CA1 region, which might be independent of LTP.     

Interaction between ellagic acid and calf thymus DNA studied with flow linear dichroism UV-VIS spectroscopy

The interaction between ellagic acid and DNA has been characterized with respect to the geometry of the ellagic acid-DNA complex, and the active form of ellagic acid has been identified. Optical spectroscopic methods have been employed to examine the interaction between double-stranded calf thymus DNA and ellagic acid in low-ionic-strength aqueous solutions at pH values of 5.5, 7.0, and 8. 8. Based on normal absorption titration and flow linear dichroism experiments, it is confirmed that the neutral form of ellagic acid present at pH 5.5 binds to double-stranded DNA. It is found that the plane of the ellagic acid chromophore is positioned at an angle relative to the DNA helix axis, which is in accordance with intercalation of ellagic acid in DNA. It is concluded that at higher values of pH no or a very limited amount of ellagic acid binds to DNA. These results prove that the direct interaction between ellagic acid and DNA must be taken into account when evaluating the mechanism underlying the observed biological effects of this plant phenol.     

Transmural Intestinal Wall Permeability in Severe Ischemia after Enteral Protease Inhibition

In intestinal ischemia, inflammatory mediators in the small intestine''s lumen such as food byproducts, bacteria, and digestive enzymes leak into the peritoneal space, lymph, and circulation, but the mechanisms by which the intestinal wall permeability initially increases are not well defined. We hypothesize that wall protease activity (independent of luminal proteases) and apoptosis contribute to the increased transmural permeability of the intestine''s wall in an acutely ischemic small intestine. To model intestinal ischemia, the proximal jejunum to the distal ileum in the rat was excised, the lumen was rapidly flushed with saline to remove luminal contents, sectioned into equal length segments, and filled with a tracer (fluorescein) in saline, glucose, or protease inhibitors. The transmural fluorescein transport was determined over 2 hours. Villi structure and epithelial junctional proteins were analyzed. After ischemia, there was increased transmural permeability, loss of villi structure, and destruction of epithelial proteins. Supplementation with luminal glucose preserved the epithelium and significantly attenuated permeability and villi damage. Matrix metalloproteinase (MMP) inhibitors (doxycycline, GM 6001), and serine protease inhibitor (tranexamic acid) in the lumen, significantly reduced the fluorescein transport compared to saline for 90 min of ischemia. Based on these results, we tested in an in-vivo model of hemorrhagic shock (90 min 30 mmHg, 3 hours observation) for intestinal lesion formation. Single enteral interventions (saline, glucose, tranexamic acid) did not prevent intestinal lesions, while the combination of enteral glucose and tranexamic acid prevented lesion formation after hemorrhagic shock. The results suggest that apoptotic and protease mediated breakdown cause increased permeability and damage to the intestinal wall. Metabolic support in the lumen of an ischemic intestine with glucose reduces the transport from the lumen across the wall and enteral proteolytic inhibition attenuates tissue breakdown. These combined interventions ameliorate lesion formation in the small intestine after hemorrhagic shock.     

C-peptide increases forearm blood flow in patients with type 1 diabetes via a nitric oxide-dependent mechanism

Proinsulin C-peptide has been shown to increase muscle blood flow in type 1 diabetic patients. The underlying mechanism is not fully understood. The aim of this study was to evaluate if the vasodilator effect of C-peptide is mediated by nitric oxide (NO). Eleven type 1 diabetic patients were studied two times and randomized to administration of intravenous and intra-arterial infusion of C-peptide or saline. Forearm blood flow (FBF) was measured by venous occlusion plethysmography during infusion of C-peptide or saline before, during, and after NO synthase (NOS) blockade. Endothelium-dependent and -independent vasodilatation was evaluated by administration of acetylcholine and sodium nitroprusside, respectively. FBF increased by 35% during intravenous C-peptide (P < 0.01) but not during saline infusion (-2%, not significant). NOS blockade resulted in a more pronounced reduction in FBF during intravenous C-peptide than during saline infusion (-41 vs. -26%, P < 0.05). Intra-arterial C-peptide failed to increase FBF during NOS blockade. However, when C-peptide was given after the recovery from NOS blockade, FBF rose by 30% (P < 0.001). The vasodilator effects of acetylcholine and nitroprusside were not influenced by C-peptide. It is concluded that the stimulatory effect of C-peptide on FBF in type 1 diabetic patients is mediated via the NO system and that C-peptide increases basal endothelial NO levels.     

Growth hormone response to thyrotropin-releasing hormone in acromegalic patients: reproducibility and dose-response study.

The aim of the study was to analyze 14 consecutive patients with active acromegaly who had not undergone any therapy, the dose response of growth hormone (GH) to thyrotropin-releasing hormone (TRH), the existence of reproducibility of such response as well as to rule out the possibility of spontaneous fluctuations of GH which would mimic this response. On several nonconsecutive days, we investigated the GH response to saline serum, 100, 200 (twice) and 400 micrograms of TRH administration. We also studied both basal serum prolactin, serum prolactin after TRH administration and thyrotropin values. Our results show an absence of GH response after saline serum infusion, whereas after TRH doses, 36.3 42.8 and 45.4% positive responses were obtained, respectively. All GH responders were concordant to the different doses administered. The mean of GH concentrations of the different doses at different times did not reach significant differences. The response to the administration of the same dose brought about a significative increase, although it was not identical. It demonstrated a progressive increase of the area under the response curve, as did the means of increments after each TRH administration, albeit without reaching statistical significance. Between the GH-responding and GH-nonresponding groups there were no differences in either basal serum prolactin or serum prolactin and thyroid-stimulating hormone levels after TRH stimulation. The present study clearly shows that TRH elicits serum GH release from GH-secreting pituitary tumors. The response was reproducible in qualitative terms rather than quantitative, and no dose-response relationship was found between the TRH concentrations and the amounts of GH secreted.     

Lowering of T3 and rise in reverse T3 induced by hyperglucagonemia: altered thyroid hormone metabolism, not altered release of thyroid hormones

Recently we reported that hyperglucagonemia induced by glucagon infusion causes a decline in serum T3 and a rise in reverse T3 in euthyroid healthy volunteers. These changes in T3 and rT3 levels were attributed to altered T4 metabolism in peripheral tissues. However, the contribution of altered release of thyroid hormones by the thyroid gland could not be excluded. Since the release of thyroid hormones is inhibited in primary hypothyroidism and is almost totally suppressed following L-thyroxine replacement therapy, we studied thyroid hormone levels for up to 6 hours after intravenous administration of glucagon in subjects with primary hypothyroidism who were rendered euthyroid by appropriate L-thyroxine replacement therapy for several years. A control study was conducted using normal saline infusion. Plasma glucose rose promptly following glucagon administration demonstrating its physiologic effect. Serum T4, Free T4, and T3 resin uptake were not altered during both studies. Glucagon infusion induced a significant decline in serum T3 (P less than 0.05) and a marked rise in rT3 (P less than 0.05) whereas saline administration caused no alterations in T3 or rT3 levels. Thus the changes in T3 and rT3 were significantly different during glucagon study when compared to saline infusion. (P less than 0.01 for both comparisons). Since, the release of thyroid hormones is suppressed by exogenous LT4 administration in these subjects; we conclude that changes in serum T3 and rT3 observed following glucagon administration reflect altered thyroid hormone metabolism in peripheral tissues and not altered release by the thyroid gland.     

Inhibition of pentagastrin-stimulated gastric acid secretion by intraileal administration of bile and elevation of plasma concentrations of gut glucagon-like immunoreactivity in anesthetized dogs

The effects of intraileal administration of bile on gastric acid secretion stimulated by a submaximal dose of intravenous pentagastrin infusion and on plasma concentrations of gut glucagon-like immunoreactivity (gut GLI) were studied in anesthetized dogs. Gastric acid secretion was measured for a 2-h period at 15-min intervals before and after intraluminal instillation of test solutions. 100 ml of canine bladder bile diluted to 10% in saline evoked a significant inhibition (20%) of gastric acid secretion. The inhibition of gastric acid secretion was accompanied by an elevation of plasma concentration of gut GLI, whereas saline instillation (in controls) caused no responses. Although the inhibition of gastric acid secretion and the elevation of plasma gut GLI are parallel phenomena, gut GLI can be reasonably postulated as one of the candidate mediators of bile-induced inhibition of gastric acid secretion, since its structurally related peptides, pancreatic glucagon, glicentin and oxyntomodulin have been reported as inhibitors of gastric acid secretion.     

Effect of preservatives on IgG aggregation, complement-activating effect and hypotensive activity of horse polyvalent antivenom used in snakebite envenomation.

Intravenous administration of antivenoms is associated with early adverse reactions in a number of cases, but the causes of this phenomenon are still unclear. The effect of preservatives (phenol and thimerosal) on IgG aggregate and dimer formation, in vitro complement-activating effect and hypotensive activity of a whole IgG horse liquid polyvalent antivenom, produced by caprylic acid fractionation, was assessed. These parameters were studied since they have been associated with the development of early adverse reactions to the administration of antivenoms and human immunoglobulins. After a three-year storage period at 4 degrees C, antivenoms with preservatives had an increased content of IgG aggregates and dimers when compared with antivenom devoid of phenol and thimerosal. These observations correlate with a slight increment in the turbidity of preservative-containing antivenoms. The three antivenoms studied (formulation: no preservatives; with phenol and thimerosal; with thimerosal alone) activated human complement in vitro, with only minor quantitative differences among them. When antivenoms were administered as a bolus intravenous injection in rats, a rapid and prominent hypotension of short duration was observed after injection of phenol-containing antivenom, whereas such an effect was absent in antivenom free of preservative and in the one containing only thimerosal. Bolus injection of saline solution with phenol resulted in a similar hypotension, indicating that the effect is due to phenol. However, when phenol-containing antivenom was diluted 1:5 with saline solution before infusion, as occurs in the clinical use of this product, no hypotension was observed. Our results stress the need to evaluate the effects of preservatives on the physicochemical and pharmacological characteristics of antivenoms.     

Interaction between veralipride and the endogenous opioid system in the regulation of body temperature in postmenopausal women

The influence of endogenous opioid peptides on body thermoregulation has been studied in untreated postmenopausal women and in the same subjects after chronic administration of the antidopaminergic drug veralipride (200 mg/day for 20 days). Subjects randomly received an infusion of the opioid antagonist naloxone (1.6 mg/h for 4 h) or saline on two consecutive days, both before and after veralipride treatment. In untreated subjects body core temperature, as evaluated by rectal temperature, did not vary during saline infusion, whereas a significant decrease was observed during naloxone infusion. Chronic administration of veralipride significantly increased the hypothermic response to naloxone. Therefore, veralipride seems to increase the activity of endogenous opioid peptides on mechanisms which regulate body temperature in postmenopausal women.     

Regulation of body temperature in postmenopausal women: interactions between bromocriptine and the endogenous opioid system

The role exerted by the endogenous opioid system on thermoregulation has been studied in nine postmenopausal women before and after the chronic administration of the dopamine agonist bromocriptine (5 mg/day). These women randomly received an infusion of the opioid antagonist naloxone (1.6 mg/h for 4 h) or saline on two consecutive days, before and after 30 days of bromocriptine administration. Body temperature as evaluated by rectal temperature, did not vary during saline infusion performed both before and after 30 days of bromocriptine administration. In untreated women naloxone infusion significantly reduced body core temperature. The hypothermic response to naloxone was significantly greater following chronic bromocriptine administration. These results indicate that bromocriptine seems to increase the activity of the endogenous opioid system on the mechanisms which regulate body temperature in postmenopausal women.     

Development of tolerance to ethanol-induced suppression of breathing movements and brain activity in the near-term fetal sheep during short-term maternal administration of ethanol

The effect of short-term maternal ethanol administration on the ethanol-induced suppression of fetal breathing movements, electrocortical (ECoG) activity, and electroocular (EOG) activity was determined in the near-term fetal sheep. Twelve conscious instrumented pregnant ewes (between 125 and 139 days of gestation; term, 147 days) received 1-h intravenous infusion of 1 g ethanol/kg total body weight daily for six days (n = 6) or an equivalent volume of normal saline daily for six days (n = 6). On the seventh day, the ethanol- and saline-pretreated animals were administered 1 g ethanol/kg total body weight. A further six ewes received 1-h intravenous infusion of 1 g ethanol/kg total body weight (n = 3) or an equivalent volume of normal saline (n = 3) daily for thirteen days with both groups receiving 1 g ethanol/kg total body weight on day fourteen. Fetal ECoG and EOG activities, and fetal breathing movements were monitored continuously over the post- operative and experimental periods. Saline infusion had no significant effect on the parameters studied. Fetal breathing movements were suppressed for 8 h after the first ethanol dose, and were not significantly suppressed after fourteen days of once-daily, maternal ethanol administration. Low-voltage ECoG and EOG activities were suppressed for 3 h after the first ethanol dose, and were not significantly suppressed after seven days of repeated ethanol administration. Maternal and fetal blood gases and acid-base balance were not significantly affected by maternal ethanol administration. These data demonstrate that short-term maternal administration of ethanol results in the development of tolerance to ethanol in the mature fetus.     

Decline of T3 and elevation in reverse T3 induced by hyperglucagonemia: changes in thyroid hormone metabolism, not altered release of thyroid hormones

Recently we reported that hyperglucagonemia induced by glucagon infusion causes a decline in serum Triiodothyronine (T3) and a rise in reverse T3 (rT3) in euthyroid healthy volunteers. These changes in T3 and rT3 levels were attributed to altered T4 metabolism in peripheral tissues. However, the contribution of altered release of thyroid hormones by the thyroid gland could not be excluded. Since the release of thyroid hormones is suppressed by exogenous administration of L-thyroxine (L-T4) in appropriate dosage, we studied thyroid hormone levels for up to 6 hours after intravenous administration of glucagon in euthyroid healthy subjects after administration of L-T4 for 12 weeks. A control study was conducted using normal saline infusion. Plasma glucose rose promptly following glucagon administration demonstrating its physiologic effect. Serum T4, Free T4 and T3 resin uptake were not altered during both studies. Glucagon infusion induced a significant decline in serum T3 (P less than 0.01) and a marked rise in rT3 (P less than 0.01) whereas saline administration caused no alterations in T3 or rT3 levels. Thus the changes in T3 and rT3 were significantly different during glucagon study when compared to saline infusion. (P less than 0.01 for both comparisons). Therefore, this study demonstrates that changes in serum T3 and rT3 caused by hyperglucagonemia may be secondary to altered thyroid hormone metabolism in peripheral tissues and not due to altered release by the thyroid gland, since the release of thyroid hormones is suppressed by exogenous L-T4 administration.     

大剂量氨甲环酸对全膝关节置换患者术后纤溶活性与炎症因子的影响

目的:探讨大剂量氨甲环酸对全膝关节置换患者术后纤溶活性与炎症因子的影响。方法:回顾性分析在我院行初次全膝关节置换术的180例患者,按照给药方式分为对照组、常规组、大剂量组,每组各60例。对照组患者直接给予生理盐水,常规组给予10 mg/kg氨甲环酸,大剂量组给予15 mg/kg氨甲环酸。比较三组术后总失血量、隐形失血量、术前与术后3天三组凝血功能(纤维蛋白原、凝血酶原时间、活化部分凝血活酶时间)、纤溶活性[纤维蛋白(原)降解产物(FDP)、D-二聚体]以及炎性因子[C-反应蛋白(CRP)、白介素-6(IL-6)]水平变化及术后2周血栓事件的发生情况。结果:大剂量组与常规组的总失血量与隐形失血量均明显低于对照组,大剂量组总失血量与隐形失血量均低于常规组(P0.05);三组患者纤维蛋白原、凝血酶原时间以及活化部分凝血活酶时间相比差异均无统计学意义(P0.05);术后3天,大剂量组和常规组FDP与D-二聚体、CRP、IL-6水平均显著低于对照组,且与常规组相比,大剂量组水平较低(P0.05);术后2周,三组肌间静脉血栓发生率比较均无显著差异(P0.05)。结论:在全膝关节置换术后使用氨甲环酸可进一步减少术后隐形失血量,且不会增加血栓事件的风险,且随着药物剂量的增加,其止血效果越强,同时具有更为显著的抗纤溶作用与抗炎效果。     

Identification of linoleic and oleic acids as endogenous Na+,K+-ATPase inhibitors from acute volume-expanded hog plasma

Na+,K+-ATPase inhibitors have been found to exist in acutely saline-infused hog plasma, which also inhibit the specific binding of ouabain to Na+,K+-ATPase and the binding of digoxin to specific anti-digoxin antibody. Two of these inhibitors were purified by a combination of Amberlite XAD-2 adsorption chromatography and 3 steps of high-performance liquid chromatography. Reverse phase, high-performance liquid chromatography, mass spectrometry, and nuclear magnetic resonance spectrometry identified these substances as linoleic (18:2) and oleic acids (18:1). A significant increase in the ouabain-displacing activity was observed in hog plasma during saline infusion. The maximal level reached was approximately 10 times higher than that of the preinfusion plasma sample. The two unsaturated fatty acids contributed to approximately 52% of the total ouabain-displacing activity after 120 min of saline infusion. The increased fatty acid levels in volume-expanded plasma are sufficient for an extensive inhibition of Na+,K+-ATPase activity. These results strongly suggest that free unsaturated fatty acids in plasma regulate extracellular fluid volume in a pathological volume-expanded condition through modulation of Na+,K+-ATPase activity.     

Quantification of deep and superficial sensibility in saline-induced muscle pain-a psychophysical study

The aim of the present study was to study the sensibility in the area of saline-induced muscle pain. In three experiments, ten subjects were exposed to computer-controlled infusion of 0.5 ml isotonic (0.9%) or hypertonic (9%) saline into the anterior tibial muscle. The pain intensity was assessed on a visual analogue scale (VAS). The pain threshold (PT) to pressure and electrical stimulation in muscle and subcutaneous tissues was determined. Three experiments were performed in which infusion of hypertonic saline produced significantly higher VAS scores than isotonic saline. In all three experiments, there was no significant difference in PT obtained after infusion of isotonic saline compared with infusion of hypertonic saline. In experiment 1, the PT was determined at the infusion site and 4 cm from the infusion site. At the infusion site, the pressure PT decreased (- 19 2%) 1, 3, 5, 7 and 9 min after infusion of isotonic and hypertonic saline, but remained unchanged 4 cm from the infusion site. The intramuscular electrical PT at the infusion site and 4 cm from the infusion site increased significantly (29 6%) 5, 7 and 9 min after saline infusion. In experiment 2, the pressure PT and the intramuscular electrical PT were recorded after two infusions of saline separated by 1 day. The day after the first infusion, the pressure PT was decreased compared with the PT before the first infusion, but the electrical PT was not affected. Moreover, the hypertonic saline infusion given on the second day produced significantly higher (130 50%) VAS scores than the infusion given on the first day. In experiment 3, the PT was determined in the subcutaneous tissue, but no significant effects of saline infusion were found. The present placebo-controlled experiments failed to show muscular or subcutaneous hyperalgesia after saline-induced muscle pain per se.     

Plasma growth hormone and somatomedin-C responses to continuous growth hormone-releasing factor infusion in normal adult men

The pituitary growth hormone (GH) responses during a 20-hour iv infusion of saline or human GH-releasing factor (hGRF-44) at 40 micrograms/h, followed by an iv bolus injection of hGRF at 2 micrograms/kg body weight, were studied in four normal adult men. During saline infusion only one or two pulses of plasma GH were observed. However, during hGRF infusion up to eight or ten pulses of GH were measured with an amplitude not different from that obtained during saline infusion. The mean +/- SEM integrated amount of GH secreted was 107 +/- 38.2 ng/ml.h in response to hGRF infusion, which was greater than the value of 25.4 +/- 3.5 ng/ml.h obtained during saline infusion. Plasma somatomedin-C also increased after hGRF infusion, but not after saline. After saline or hGRF infusion most of the subjects still responded to an iv bolus injection of the peptide (2 micrograms/kg). These results indicate that hGRF infusion augments GH secretion by increasing the number, but not the amplitude of GH pulses and that the infusion does not cause the pituitary somatotrophs to lose their capacity and ability to respond to hGRF subsequently.