Small Fall Research Articles

Physiological insulin action is opposed by beta-adrenergic mechanisms in dogs.

To investigate the possible role of adrenergic mechanisms in modulating glucose homeostasis during physiological insulin changes, we studied the effects of alpha-, beta-, or combined alpha- and beta-adrenergic blockade on glucose production (Ra) and utilization (Rd) via isotope ([3-(3)H]glucose) dilution during nonstressful, nonhypoglycemic conditions in response to physiological insulin changes in conscious dogs. Without adrenergic blockade, infusion of insulin at 0.275 mU.kg-1.min-1 (control) caused glucose to fall from 92 +/- 4 to 82 +/- 4 mg/dl over 30 min, because of transient fall in Ra from 2.8 +/- 0.4 to 2.3 +/- 0.3 mg.kg-1.min-1, which recovered to base line by 30 min. There was a later rise in Rd to 3.9 +/- 0.4 mg.kg-1.min-1 at 45 min, but no counter-regulatory hormonal changes (glucagon, cortisol, epinephrine, and norepinephrine) to account for these findings in glucose kinetics. alpha-Blockade alone led to an initial rise in base-line insulin and consequent fall in glucose, associated with a transient fall in Ra but no change in Rd; infusion of insulin led to a further small fall in glucose, with no change in Ra, but with a rise at 30 min in Rd similar to controls. beta-Blockade alone led to an initial fall in insulin and modest rise in glucose; insulin infusion led to a greater rate of fall in glucose than in controls (from 112 +/- 6 to 78 +/- 7 mg/dl over 30 min).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of naloxone on haemodynamic responses to acute blood loss in unanaesthetized rabbits.

1. We have tested the hypothesis that the pressor action of (-) naloxone HC1 after haemorrhage is due to antagonism of endogenous opiate mechanisms that are activated by haemorrhage, rather than to some more direct vasoconstrictor action of the drug. 2. Six conscious rabbits were treated intravenously with either naloxone (4 mg kg-1, then 0.1 mg kg-1 min-1) or equivalent volumes of saline. In unbled rabbits the naloxone regimen had no effect except to cause a transient bradycardia. After each treatment the rabbits were bled at a rate of 2.45 ml kg-1 min-1 until blood pressure fell to 40 mmHg or 28 ml kg-1 of blood had been withdrawn (17-24 ml kg-1 after saline, 21-28 ml kg-1 after naloxone). 3. Throughout both episodes of bleeding there was a progressive fall of cardiac output and rise of heart rate, at rates that were constant and independent of the prior treatment. 4. After saline treatment, bleeding at first resulted in a steep and progressive fall of systemic vascular conductance and a small fall in blood pressure. However, when blood loss exceeded 12.7 ml kg-1 (approximately 28% of blood volume) there was an abrupt rise in systemic vascular conductance and an abrupt fall in blood pressure. 5. After naloxone treatment, during the entire period of bleeding systemic vascular conductance fell steeply and blood pressure fell slowly. 6. The different effects of saline and naloxone on the haemodynamic responses to acute blood loss were not explicable by differences in haematocrit or net blood volume. 7. We conclude that endogenous opiate mechanisms are responsible for the abrupt vasodilation that occurs when more than 28% of blood volume is withdrawn rapidly from conscious rabbits. We suggest that these mechanisms reside in the central nervous system.

Ketoconazole-induced reduction in serum 1,25-dihydroxyvitamin D and total serum calcium in hypercalcemic patients.

Administration of the antifungal drug ketoconazole reduces serum 1,25-dihydroxyvitamin D (1,25-D) levels in normal subjects. To determine whether a similar effect occurs in hypercalcemic patients, ketoconazole (200 mg every 8 h for 7 days) was given to nine patients with confirmed primary hyperparathyroidism, three patients with probable primary hyperparathyroidism who were awaiting surgery, and three patients with mild hypercalcemia of uncertain etiology who were being followed. Ketoconazole administration led to a significant reduction in mean serum 1,25-D levels in the hypercalcemic patients [basal, 64 +/- 7 (+/- SEM) pg/mL (154 +/- 17 pmol/L) vs. 36 +/- 5 pg/mL (86 +/- 12 pmol/L) after ketoconazole; P less than 0.001]. Serum total calcium fell slightly but significantly [basal, 11.05 +/- 0.17 mg/dL (2.76 +/- 0.04 mmol/L) vs. 10.77 +/- 0.16 (2.69 +/- 0.04 mmol/L) after ketoconazole; P less than 0.02], but the falls in total serum calcium and serum 1,25-D after ketoconazole treatment were not correlated with one another. Ketoconazole administration did not alter serum ionized calcium, 25-hydroxyvitamin D, phosphate, alkaline phosphatase, or PTH concentrations or urinary cAMP excretion. The responses to ketoconazole were similar in all three patient subgroups. We conclude that short term administration of ketoconazole to hypercalcemic patients causes a substantial fall in serum 1,25-D and a small fall in total serum calcium. These effects render ketoconazole a potentially useful agent for investigation of the importance of 1,25-D in patients with hypercalcemic disorders and for their treatment.

The Effect of Nitrendipine (NIT) on Maternal and Fetal Blood Pressure, Uterine Blood Flow, and Blood Gas Status in Pregnant Sheep

Ewes of between 126-134 days of gestation (term 147 days) were anesthetized and underwent vascular cannula placement in the maternal and fetal jugular vein and carotid artery. A flow probe was placed around the uterine artery supplying the pregnant horn. A median of 7 days after surgery, the effect of nitrendipine (NIT) (2-8 micrograms/kg/min in stepwise increments of 30 min each followed by a 2-h recovery period) on maternal and fetal systemic arterial blood pressure (BP), heart rate (HR), the uterine blood flow (UBF), and blood gas tensions was determined (n = 5 experiments). Control experiments (n = 4) in which vehicle only was infused were also performed. The infusion of NIT was associated with a small fall in maternal systolic BP and a progressive fall in maternal diastolic BP (p less than 0.01, less than 0.001; two-way ANOVA); UBF did not change. Fetal systolic BP actually rose during the NIT infusion (p less than 0.02) but there was no difference in fetal diastolic BP. Both maternal and fetal HR rose in the NIT group. Fetal pH remained very stable throughout as did PaCO2. Fetal PaO2 fell somewhat during the recovery stages in both NIT and control groups. There is considerable interest in the possible use of calcium channel blockers in treating pregnancy-induced hypertension. These preliminary experiments provide no evidence in conflict with such a use.

Is the antiproteinuric effect of dipyridamole hemodynamically mediated?

We studied the acute antiproteinuric and renal hemodynamic effect of dipyridamole 30-60 mg intravenously in 13 salt-depleted patients with the nephrotic syndrome of different etiology. Whereas mean arterial pressure did not change, a small fall in glomerular filtration rate with a concomitant fall in filtration fraction and a decrease in urinary protein loss occurred. The fall in filtration fraction was positively correlated with the fall in proteinuria. This suggests that the antiproteinuric effect of dipyridamole is at least partly due to an efferent vasodilation with a fall in intraglomerular capillary pressure.

Effects of stimulation of nasal and superior laryngeal inputs on the hindlimb vasculature of anaesthetized cats.

1. In chloralose-anaesthetized artificially ventilated cats, either stimulation of the nasal mucosae with water or electrical stimulation of the superior laryngeal nerve (s.l.n.) resulted in apnoea, as measured from the phrenic nerve activity, and a rise in perfusion pressure of a hindlimb perfused at constant flow. In the absence of changes in venous pressure this vascular response would indicate vasoconstriction in the hindlimb. There was, however, no significant change in either heart rate or arterial blood pressure. 2. Simultaneous stimulation of the nasal mucosae and s.l.n. also resulted in apnoea but with a larger hindlimb vasoconstriction than was obtained with stimulation of only one input. This increased vasoconstriction was not significantly different from the one which in theory could be obtained by summing the two individual responses from stimulation of the nasal mucosae or s.l.n. 3. In cats anaesthetized with chloralose-urethane, stimulation of the nasal mucosae or s.l.n. also evoked an apnoea and hindlimb vasoconstriction. However, in these animals this was accompanied by a bradycardia and small fall in arterial blood pressure. 4. The present results show that whilst stimulation of two parts of the upper respiratory tract evokes qualitatively similar responses in the hindlimb vasculature, simultaneous activation of the two stimuli does not appear to result in facilitation of this hindlimb vasoconstrictor response, simply an addition of those obtained on separate stimulation. The bradycardia evoked in response to upper airway stimulation is dependent on the anaesthetic used and in the present experiments could only be obtained in animals anaesthetized with choralose-urethane.

Antagonistic controls regulate copy number of the yeast 2 mu plasmid.

The endogenous 2 mu plasmid of yeast encodes a site-specific recombinase FLP that can cause an amplification of plasmid copy number. Using strains overexpressing 2 mu plasmid proteins from chromosomal constructs to disrupt the normal balance of gene products, we show here that copy number is controlled by regulating the transcript level of FLP. Expression of FLP is negatively regulated over a 100-fold range by the joint action of the plasmid-encoded REP1 and REP2 proteins, which also have a role in plasmid partition. We also show that the product of the fourth plasmid open reading frame D increases FLP expression by relieving the repression caused by REP1 and REP2. This is the first demonstration of a function for this gene, which we call RAF. The transcription of RAF is also repressed by REP1 and REP2 acting together, but requires a higher level for complete inhibition than that required to repress FLP. Copy number is therefore negatively regulated by REP1-REP2 concentration both by direct repression of FLP and indirectly, by control of the positive element, the anti-repressor RAF. We propose that these antagonistic regulatory mechanisms amplify the signal produced by a small fall in copy number.

Antimuscarinic premedication in canine anaesthesia: a comparison of atropine, hyoscine and glycopyrrolate

ABSTRACTAnticholinergic drugs are commonly given as preanaesthetic medication to reduce secretions and bradycardia. In this trial, clinical cases were given atropine, hyoscine or glycopyrrolate on a logarithmic dose scale. Another group was not given any anticholinergic agent. Anaesthesia was induced with thiopentone and maintained with halothane in oxygen and nitrous oxide. All the anticholinergic drugs decreased salivation although there was also a small fall in salivation in the control group. Pulse rates rose on induction and fell over the course of anaesthesia in the control group but the mean pulse rates did not fall below the normal range. Atropine and hyoscine produced a tachycardia followed by a fall in pulse rate similar to the control group during anaesthesia. Glycopyrrolate maintained the pulse at the same level throughout. In view of the disadvantages of tachycardia, glycopyrrolate is probably the anticholinergic agent of choice when such a drug is indicated.

Hemodynamic Effects of a New Angiotensin Converting Enzyme Inhibitor, Spirapril, in Sodium-Loaded and Sodium-Depleted Rabbits

The new angiotensin converting enzyme inhibitor, spirapril, was found to inhibit the pressor effects of angiotensin I about 10 times more potently than captopril in conscious rabbits. Its effects on systemic hemodynamics and regional blood flows were studied in two groups of 8 normotensive anaesthetized rabbits pretreated 24 h before the acute experiment either by substituting 0.45% NaCl for drinking water or with a subcutaneous injection of 20 mg kg-1 furosemide. Under barbiturate anaesthesia, regional blood flows were then measured with microspheres before and after i.v. administration of two doses of spirapril. With anaesthesia and surgery, plasma renin activity (PRA) was elevated in the salt-replete group and very high in the salt-depleted group (37 and 152 ng ml-1 h-1, respectively). Spirapril lowered blood pressure more in salt-depleted animals and increased only cardiac output and renal blood flow in salt-replete ones. Weak cardiodepression, associated with a small fall of cardiac output, was found in salt-depleted rabbits, indicating that very high angiotensin II levels may contribute to maintain cardiac function in volume-depleted animals with an activated sympathetic system. Coronary and skin blood flow decreased, and pancreatic and hepatic artery flow increased only in this group. A change in the salt balance can thus cause major differences in the responses of the peripheral circulation to angiotensin converting enzyme inhibition.

Evidence that the flux control coefficient of the respiratory chain is high during gluconeogenesis from lactate in hepatocytes from starved rats. Implications for the hormonal control of gluconeogenesis and action of hypoglycaemic agents.

1. Increasing concentrations of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), a mild respiratory-chain inhibitor [Halestrap (1987) Biochim. Biophys. Acta 927, 280-290], caused progressive inhibition of glucose production from lactate + pyruvate by hepatocytes from starved rats incubated in the presence or absence of oleate and gluconeogenic hormones. 2. No significant changes in tissue ATP content were observed, but there were concomitant decreases in ketone-body output and cytochrome c reduction and increases in NADH fluorescence and the ratios of [lactate]/[pyruvate] and [beta-hydroxybutyrate]/[acetoacetate]. 3. The inhibition by DCMU of palmitoylcarnitine oxidation by isolated liver mitochondria was used to calculate a flux control coefficient of the respiratory chain towards gluconeogenesis. In the presence of 1 mM-oleate, the calculated values were 0.61, 0.39 and 0.25 in the absence of hormone and in the presence of glucagon or phenylephrine respectively, consistent with activation of the respiratory chain in situ as previously suggested [Quinlan & Halestrap (1986) Biochem. J. 236, 789-800]. 4. Cytoplasmic oxaloacetate concentrations were shown to decrease under these conditions, implying inhibition of pyruvate carboxylase. 5. Inhibition of gluconeogenesis from fructose and dihydroxyacetone was also observed with DCMU and was accompanied by an increased output of lactate + pyruvate, suggesting that activation of pyruvate kinase was occurring. With the latter substrate, measurements of tissue ADP and ATP contents showed that DCMU caused a small fall in [ATP]/[ADP] ratio. 6. Two inhibitors of fatty acid oxidation, pent-4-enoate and 2-tetradecylglycidate, were shown to abolish and to decrease respectively the effects of hormones, but not valinomycin, on gluconeogenesis from lactate + pyruvate, without changing tissue ATP content. 7. It is concluded that the hormonal increase in mitochondrial matrix volume stimulates fatty acid oxidation and respiratory-chain activity, allowing stimulation of pyruvate carboxylation and thus gluconeogenesis to occur without major changes in [ATP]/[ADP] or [NADH]/[NAD+] ratios. 8. The high flux control coefficient of the respiratory chain towards gluconeogenesis may account for the hypoglycaemic effect of mild respiratory-chain inhibitors.

Influence of sodium‐hydrogen exchange on intracellular pH, sodium and tension in sheep cardiac Purkinje fibres.

1. The influence of sarcolemmal Na+-H+ exchange upon intracellular Na+ activity (aiNa), intracellular pH (pHi), extracellular surface pH (pHs) and tonic tension was investigated in sheep cardiac Purkinje fibres. Intracellular ion activities were measured with liquid sensor ion-selective micro-electrodes. A two-micro-electrode voltage-clamp was also used to control membrane potential while simultaneously recording tonic tension. 2. Inhibition of the sarcolemmal Na+-K+ pump by strophanthidin (10 mumol/l) produced a rise in aiNa, an increase in [Ca2+]i as evidenced by a rise in tonic tension, and a fall in pHi of 0.1-0.3 units. The intracellular acidosis has been shown previously to be linked to the rise in [Ca2+]i (Vaughan-Jones, Lederer & Eisner, 1983). 3. Amiloride (1-2 mmol/l), an inhibitor of Na+-H+ exchange, produced a small reversible decrease in pHi and aiNa. Both effects became more pronounced in strophanthidin-exposed fibres. In addition, pHi decreased during application of strophanthidin and this decrease was reversibly inhibited by amiloride. It is concluded that sarcolemmal Na+-H+ exchange is stimulated following inhibition of the Na+-K+ pump. 4. In strophanthidin-exposed fibres, a rise in [Ca2+]i resulted in an intracellular acidosis which could still be observed in the presence of amiloride (1 mmol/l). This suggests that the fall in pHi was not caused by a modulatory effect of [Ca2+]i on sarcolemmal Na+-H+ exchange. 5. Tetrodotoxin (TTX) produced a small fall in aiNa (ca. 0.5 mmol/l) which was not augmented in the presence of strophanthidin. Furthermore, the effects on aiNa of TTX and amiloride were additive. Thus the influence of amiloride on aiNa does not involve blockade of voltage-gated Na+ channels. 6. The stoicheiometry of Na+-H+ exchange, estimated from the rates of change of pHi and aiNa in amiloride, appeared to be electroneutral (1:1). The stoicheiometry was unaffected by changes in pHi. 7. In strophanthidin-exposed fibres (i.e. aiNa is elevated), the recovery of pHi from an intracellular acidosis (brought about by brief exposure to NH4Cl) was slowed greatly by amiloride (1-2 mmol/l). The rise in aiNa that occurred during pHi recovery was also reduced by amiloride. It is concluded that Na+-H+ exchange can be stimulated by a fall in pHi under conditions where aiNa is elevated. However, at a given pHi, its rate of recovery was slower in the presence than in the absence of strophanthidin.(ABSTRACT TRUNCATED AT 400 WORDS)

Mucosal surface pH of the large intestine of the rat and of normal and inflamed large intestine in man.

The surface pH of rat distal colonic mucosa and human rectal mucosa was measured in vitro using first a small pH electrode with a flattened tip. In buffer with pH 7.56 the mean rat colonic surface pH was 6.72. Lowering the buffer pH in steps resulted in a small fall in surface pH, the values being buffer pH 7.06 surface pH 6.64, buffer pH 6.58 surface pH 6.61 and finally buffer pH 6.09 surface pH 6.39. Similar results were obtained with a buffer where butyrate, 30 mmol/l replaced chloride and when a CO2/bicarbonate buffer was used. During the time taken for the study transmural potential difference only changed by 1-2 mV. Serosal surface pH changed with buffer pH, suggesting that the maintained surface pH is a property of the mucosal surface only. The surface pH of human rectal mucosa was similar to that of rat distal colonic mucosa. As buffer pH fell from pH 7.51 to 5.96 mucosal surface pH only fell from pH 6.80 to 6.26. The values obtained in ulcerative proctitis did not differ from normal mucosa. Secondly pH microelectrodes were used to measure the juxta mucosal pH and the pH-microclimate thickness when luminal pH was controlled. The microclimate had a pH 6.63 adjacent to the mucosa with a thickness of 840 micron. The importance of mucus in maintaining the microclimate was shown by n-acetyl cysteine thinning and prostaglandin E2 thickening the layer. These results describe a surface microclimate in the large intestine of appreciable thickness and a constant juxta mucosal pH. Luminal pH changes produce only a small change in microclimate pH.

Arterial oxygen saturation and breathlessness in patients with chronic obstructive airways disease.

Nine patients with chronic obstructive airways disease performed a 6 min self-paced walk (breathing air) on a treadmill and then identical (but operator-controlled) treadmill walks breathing either air or supplemental oxygen sufficient to just prevent arterial oxygen desaturation during the exercise. During the exercises, ventilation was recorded and patients recorded their sensation of breathlessness on a visual analogue scale (VAS) every 30 s. Breathing supplemental oxygen produced a small fall in mean exercise ventilation and a large and consistent reduction in mean exercise breathlessness. In seven patients the VAS scores were higher on air than with supplemental oxygen, at similar levels of ventilation. An analysis of covariance, to control for reduction in ventilation, showed a decrease in mean breathlessness when breathing supplemental oxygen, significant at the 8% level. The reduction in breathlessness produced by preventing exercise desaturation cannot be explained by the decrease in ventilation. This suggests that hypoxia may be a stimulus for breathlessness. The mechanism is unknown.

Lack of effect of atrial natriuretic peptide on vasopressin release.

This study was designed to investigate the effects of intracerebroventricular or intravenous atrial natriuretic peptide (ANP) on plasma arginine-vasopressin (AVP) levels, plasma renin activity (PRA), blood pressure (BP) and heart rate (HR) in conscious rats. No changes were observed in plasma AVP levels and PRA after intracerebroventricular injection of ANP (0.3 nmol/kg). Also no changes were found in BP and HR after intracerebroventricular ANP injection in the dose range 0.01-0.3 nmol/kg. No significant changes were observed in plasma AVP levels after the intravenous administration of ANP at 2.5 nmol/kg to hydrated rats or at 0.1 nmol/kg and 2.5 nmol/kg to dehydrated rats, although the larger dose was sufficient to cause a small fall in BP. Even after 30 min intravenous infusion of ANP at 0.1 nmol min-1 kg-1, a dose sufficient to produce very high plasma ANP levels, no change in plasma AVP could be detected, although haemodynamic changes were observed. Intravenous ANP injection (2.5 nmol/kg) inhibited basal renin secretion in hydrated rats and also inhibited renin secretion which had been stimulated by prior dehydration. From these studies in hydrated and dehydrated rats, there was no evidence that either intracerebroventricular or intravenous ANP administration affected AVP release in vivo.

Cardiovascular effects and safety of intravenous and intramuscular pentamidine isethionate.

Intramuscular (im) pentamidine isethionate can cause substantial local pain and inflammation at the injection site. This drug is being used more frequently in recent years to treat Pneumocystis pneumonia, particularly in patients with acquired immunodeficiency syndrome. Clinicians began administering it iv despite warnings that iv administration might cause severe hypotension. We investigated the safety of im and iv pentamidine, monitoring hemodynamics after each dose in 11 patients with intra-arterial lines. Results showed only a small (but statistically significant) fall in mean arterial pressure after both im and slow (60 min) iv administration. A concomitant decrease in pulse occurred, but no change in cardiac output, pulmonary capillary occlusion pressure or systemic vascular resistance was noted. These results suggest that it may be safe to infuse pentamidine slowly intravenously. This route is more comfortable to patients than im administration.

Effect of substance P on cardiovascular and respiratory function in subjects

The effect of substance P (SP), administered both intravenously and by inhalation, has been studied in normal and asthmatic humans. Intravenous infusion of SP (0.2-3.3 pmol X kg-1 X min-1) achieving a plasma concentration of SP between 5 and 25 pM produced vasodilatation (mean +/- SD), maximal increase in skin temperature (0.9 +/- 0.3 degree C) (P less than 0.05), and fall in diastolic blood pressure (8.5 +/- 2.9 mmHg) (P less than 0.05) associated with an increase in heart rate (15 +/- 10 beats/min) (P less than 0.05). All subjects had a fall in Vp30 (airflow at 70% of forced vital capacity measured from total lung capacity after a forced partial expiratory flow maneuver) at low infusion rate (P less than 0.05) and a significant rise at the highest infusion rate (P less than 0.05). Ventilation at rest and when stimulated by transient hypoxia increased (mean increase in resting ventilation 0.73 +/- 0.4 l/min and mean percent increase in transient ventilatory hypoxic response 41 +/- 27%). There was a small nonsignificant increase in plasma norepinephrine but no change in epinephrine or histamine. Inhaled SP, up to 0.7 mumol, caused a small nonsignificant fall in airway function in asthmatic subjects. SP has demonstrable effects on vascular smooth muscle and control of ventilation but at the doses studied had little effect on airway function.

Derivation of CO2 output from oscillations in arterial pH.

Theory predicts that the rate of rise of the oscillation in arterial CO2 partial pressure (PaCO2) is linearly dependent on CO2 flux from venous blood to alveolar gas. We have measured, in the anesthetized cat, CO2 output (VCO2) and oscillations in arterial pH. The pH signal was differentiated to give the maximum rate of fall of pH on the downstroke of the oscillation (dpH/dt decreases max). Since oscillations in pH are due to oscillations in arterial PCO2, dpH/dt decreases max was considered to be equivalent to the maximum rate of rise of the PCO2 oscillation. VCO2 was increased by ventilating the intestines with CO2 and by the intra-arterial infusion of 2,4-dinitrophenol. VCO2 was decreased by filling the intestines with isotonic tris(hydroxymethyl)methylamine buffer. The maximum range of VCO2 covered was 7.8-51 ml/min, and the mean range was from 13.6 +/- 1.3 to 29.7 +/- 1.6 (SE) ml/min. Although CO2 loading produced a small rise and CO2 unloading a small fall in mean PaCO2, the changes were not statistically significant, so that overall the response was close to isocapnia. Over the limited range of VCO2 studied there was a highly significant linear association between dpH/dt decreases max and VCO2 which supports the contention that the slope of the upstroke of the PaCO2 oscillation is determined by the CO2 flux from mixed venous blood to alveolar gas. As such this slope is a potential chemical signal linking ventilation to CO2 production.

Effect of cold and warm dry air hyperventilation on canine airway blood flow.

Tracheobronchial blood flow increases with cold air hyperventilation in the dog. The present study was designed to determine whether the cooling or the drying of the airway mucosa was the principal stimulus for this response. Six anesthetized dogs (group 1) were subjected to four periods of eucapnic hyperventilation for 30 min with warm humid air [100% relative humidity (rh)], cold dry air (-12 degrees C, 0% rh), warm humid air, and warm dry air (43 degrees C, 0% rh). Five minutes before the end of each period of hyperventilation, tracheal and central airway blood flow was determined using four differently labeled 15-micron diam radioactive microspheres. We studied another three dogs (group 2) in which 15- and 50-micron microspheres were injected simultaneously to determine whether there were any arteriovenous communications in the bronchovasculature greater than 15 micron diam. After the last measurements had been made, all dogs were killed, and the lungs, including the trachea, were excised and blood flow to the trachea, left lung bronchi, and parenchyma was calculated. Warm dry air hyperventilation produced a consistently greater increase in tracheobronchial blood flow (P less than 0.01) than cold dry air hyperventilation, despite the fact that there was a smaller fall (6 degrees C) in tracheal tissue temperature during warm dry air hyperventilation than during cold dry air hyperventilation (11 degrees C), suggesting that drying may be a more important stimulus than cold for increasing airway blood flow. In group 2, the 15-micron microspheres accurately reflected the distribution of airway blood flow but did not always give reliable measurements of parenchymal blood flow.

Cellular and subcellular localization of the bactericidal/permeability- increasing protein of neutrophils

Human and rabbit polymorphonuclear leukocytes contain a bactericidal/permeability-increasing protein (BPI), a potent cytotoxin active specifically against gram-negative bacteria. To identify the cell population(s) producing BPI, we have examined mature and immature human blood cells for BPI by immunofluorescence of intact cells and radioimmunoassay and bioassay of cell extracts. By immunofluorescence and radioimmunoassay of cells from peripheral blood, BPI was detected only in neutrophils; immunofluorescent staining was punctate, indicative of the granule localization of BPI. Nearly all (greater than 90%) BPI was recovered during the subcellular fractionation of neutrophils (N2 cavitation and discontinuous Percoll gradient) in fractions containing primary granules. Little BPI was released from intact cells during degranulation (cytochalasin B and f-Met-Leu-Phe) or could be extracted from isolated granules with salt or weak acid, which suggests that most granule-associated BPI is membrane bound. Double staining of bone marrow smears for BPI and lactoferrin revealed BPI only in neutrophil precursors including (pro)myelocytelike cells lacking lactoferrin, a marker of neutrophil secondary granules. Of several human cell lines tested, only the promyelocytelike HL-60 (and to a lesser extent, KG-1) cells contained BPI. BPI was present in a more mature subpopulation (less than 25%) of untreated HL-60 cells, recognized by surface marker analysis (rosetting with IgG-sensitized sheep RBC, the absence of proliferation-associated cell surface antigen). Induction of neutrophilic or monocytic differentiation caused, respectively, a small (approximately 50%) rise or fall in the BPI content. These findings indicate that BPI is a specific product of the neutrophil lineage and, hence, of the specialized cytotoxic apparatus of the neutrophil that plays an essential role in host defense v gram-negative bacteria.

Cellular and Subcellular Localization of the Bactericidal/Permeability-Increasing Protein of Neutrophils

Human and rabbit polymorphonuclear leukocytes contain a bactericidal/permeability-increasing protein (BPI), a potent cytotoxin active specifically against gram-negative bacteria. To identify the cell population(s) producing BPI, we have examined mature and immature human blood cells for BPI by immunofluorescence of intact cells and radioimmunoassay and bioassay of cell extracts. By immunofluorescence and radioimmunoassay of cells from peripheral blood, BPI was detected only in neutrophils; immunofluorescent staining was punctate, indicative of the granule localization of BPI. Nearly all (greater than 90%) BPI was recovered during the subcellular fractionation of neutrophils (N2 cavitation and discontinuous Percoll gradient) in fractions containing primary granules. Little BPI was released from intact cells during degranulation (cytochalasin B and f-Met-Leu-Phe) or could be extracted from isolated granules with salt or weak acid, which suggests that most granule-associated BPI is membrane bound. Double staining of bone marrow smears for BPI and lactoferrin revealed BPI only in neutrophil precursors including (pro)myelocytelike cells lacking lactoferrin, a marker of neutrophil secondary granules. Of several human cell lines tested, only the promyelocytelike HL-60 (and to a lesser extent, KG-1) cells contained BPI. BPI was present in a more mature subpopulation (less than 25%) of untreated HL-60 cells, recognized by surface marker analysis (rosetting with IgG-sensitized sheep RBC, the absence of proliferation-associated cell surface antigen). Induction of neutrophilic or monocytic differentiation caused, respectively, a small (approximately 50%) rise or fall in the BPI content. These findings indicate that BPI is a specific product of the neutrophil lineage and, hence, of the specialized cytotoxic apparatus of the neutrophil that plays an essential role in host defense v gram-negative bacteria.