Circulating atrial natriuretic factor activates vagal afferent inputs to paraventriculo-spinal neurones in the rat.

In urethane-anaesthetised, paralysed and artificially ventilated rats (300-350 g b.wt.), i.

Effects of volume loading on paraventriculo-spinal neurones in the rat.

Experiments were carried out to investigate the effects of volume loading on the activity of antidromically identified paraventriculo-spinal neurones in rats anaesthetised with urethane. Intravenous infusion of isotonic saline (1.5-4.

Patterns of activity in sympathetic postganglionic nerves to skeletal muscle, skin and kidney during stimulation of the medullary raphe area of the rat.

In chloralose/urethane anaesthetised rats multi and single fibre activity was recorded in renal sympathetic nerves and in sympathetic nerves to skeletal muscle and to the skin of the hind limb. The activity was pulse-modulated and inhibited by stimulating baroreceptors with an increase in blood pressure following i.v.

A comparison of the effects of intrathecally administered 5-hydroxytryptamine and thyrotropin-releasing hormone on renal and muscle sympathetic nerve activity.

Thyrotropin-releasing hormone (TRH) has been shown to coexist with 5-hydroxytryptamine (5-HT) in spinally projecting raphe neurones, some of which terminate in the sympathetic nuclei of the spinal cord. In an attempt to mimic the actions of these neurones, the effects of intrathecal administration of 5-HT was compared to that of TRH on activity in two sympathetic postganglionic nerves, the renal nerve and sympathetic fibres to skeletal muscle of the hind limb. In chloralose-urethane anaesthetised rats intrathecal infusion of TRH at the T9 level in doses of 5-30 micrograms increased activity in renal nerve as did low doses (20-100 micrograms) of 5-HT.

Altitude insomnia: studies during an expedition to the Himalayas.

During an expedition to the Himalayas, we studied the sleep and respiration of six climbers. Three ingested acetazolamide (500 mg) daily throughout the climb and the other three ingested placebo. At high altitude (4,150-4,846 m), each subject ingested temazepam (10 mg) for one night and placebo for another.

Electrophysiological properties of paraventriculo-spinal neurones in the rat.

In rats anaesthetized with urethane, electrical stimulation of the thoracic cord at T9-10 evoked antidromic response in neurones in the parvocellular portion of the ipsilateral paraventricular nucleus. Estimated conduction velocities in the spinally-projecting axons ranged from 0.6-5.

Effects of activating spinal alpha-adrenoreceptors on sympathetic nerve activity in the rat.

The effects of several alpha-adrenoreceptor agonists and antagonists administered intrathecally at T10 level on renal sympathetic nerve activity (RSNA) were examined, in chloralose-urethane anaesthetised rats. Intrathecal noradrenaline (NA, 0.5-500 micrograms) produced one of 3 responses depending on dose, an inhibition of RSNA at low doses, an excitation of RSNA at high doses, or a biphasic effect.

Cloning of the adenylate cyclase genetic determinant of Bordetella pertussis and its expression in Escherichia coli and B. pertussis.

A recombinant plasmid, pRMB1, identified from a gene library of B. pertussis, restored adenylate cyclase (AC) and haemolysin (HLY) activities to B. pertussis BP348 (a Tn5-insertion mutant deficient in both these activities).

Excitatory and inhibitory actions of intrathecally administered 5-hydroxytryptamine on sympathetic nerve activity in the rat.

In chloralose/urethane anaesthetised rats the effect of intrathecal (i.t.) administration of 5-hydroxytryptamine (5-HT) on activity in sympathetic nerves to the kidney was studied.

The action of a substance P antagonist on sympathetic nerve activity in the rat.

In anaesthetised rats recordings were made of sympathetic activity in renal nerves whilst studying the effects of intrathecal injection of the substance P antagonist (D-Arg1, D-Pro2, D-Trp7,9, Leu11)-substance P on the responses to, stimulation of the ventrolateral medulla, to intrathecal injection of substance P, serotonin and glutamate. All responses were abolished by the antagonist.

Intrathecally administered angiotensin II increases sympathetic activity in the rat.

The possibility that angiotensin II (AII) functions as an excitatory transmitter on sympathetic preganglionic neurones was tested in anaesthetized rats. Drugs were administered intrathecally whilst recording blood pressure, heart rate and sympathetic activity in splanchnic or renal nerves. Intrathecal AII (20 microliters, 10(-5) M) caused a significant increase in blood pressure of 13% +/- 3 and in sympathetic activity of 15% +/- 5.

The effect of acetazolamide on breath holding at high altitude.

The effect of altitude and acetazolamide on breath holding was studied in 20 individuals. Breath holding time was reduced progressively during ascent. There was an additional reduction in the acetazolamide group at low but not at high altitude.

Blood lactate changes during exercise at high altitude.

Blood lactate concentrations were measured in 18 normal subjects at the end of an exercise test designed to maintain heart rate at 85% of maximum for 15 minutes. Blood lactate concentrations were reduced at high altitude (4846 m) and correlated positively with basal pH and negatively with basal Pa,O2 levels. Blood lactate concentrations tended to be lower in those subjects on acetazolamide but were not correlated with the severity of acute mountain sickness or with the workload of the exercise test.

The BMRES 1984 Medical Research Expedition to the Himalayas.

Twenty-one subjects formed a trekking expedition to study the effects of acetazolamide on exercise performance and acclimatization at high altitude. Subjects were randomized to acetazolamide or placebo on a double blind basis. During ascent to and stay for 6 nights at 4846 m studies were carried out on blood gases, 2,3 diphosphoglycerate (2,3 DPG), proteinuria, exercise testing, intestinal absorption, purine metabolism and changes in body composition.

The central site of the sympatho-inhibitory action of 5-hydroxytryptamine in the cat.

The aim of this study was to determine the site in the CNS at which 5-hydroxytryptamine (5-HT) inhibits efferent sympathetic nerve activity in the cat. 5-Hydroxytryptamine (3 and 10 micrograms/kg), given into the lateral cerebral ventricle, produced immediate non dose related increases in mean blood pressure (MBP), heart rate (HR) and renal nerve activity (RNA). Larger doses (30 and 100 micrograms/kg i.

Complementation of mutations in Escherichia coli and Bordetella pertussis by B. pertussis DNA cloned in a broad-host-range cosmid vector.

A gene library of Bordetella pertussis DNA was constructed in Escherichia coli using the broad-host-range cosmid vector pLAFR1. The average insert size was 24.9 kb.

R-plasmid-mediated chromosome mobilization in Bordetella pertussis.

Antibiotic-resistant and auxotrophic mutants of Bordetella pertussis were isolated. These were used as recipients for the uptake from Escherichia coli of broad-host-range R plasmids R68.45, RP1, and RP1 and RP4 carrying transposons Tn501 and Tn7 respectively.

A ventromedullary relay involved in the hypothalamic and chemoreceptor activation of sympathetic postganglionic neurones to skeletal muscle, kidney and splanchnic area.

Bilateral application of glycine to the ventral surface of the medulla produces a profound hypotension during which sympathetic vasoconstrictor activity to splanchnic, renal and skeletal muscle vascular beds is reduced. The pattern of activation of sympathetic vasoconstrictor fibres to kidney and skeletal muscle, during carotid chemoreceptor activation and hypothalamic stimulation, is attenuated as tonic sympathetic activity diminishes. Functioning ventromedullary neurones are thus necessary for maintaining tonic sympathetic nerve activity, and for reflex and brain evoked patterns of sympathetic nerve activity, in the anaesthetized cat.

Discharge patterns in postganglionic neurones to skeletal muscle and kidney during activation of the hypothalamic and midbrain defence areas in the cat.

Electrical stimulation of hypothalamic and midbrain defence area sites eliciting a cholinergic vasodilatation in the hindlimb activates vasodilator fibres supplying skeletal muscle. Simultaneous baroreceptor mediated suppression of sympathetic vasoconstrictor activity to the muscle and postfiring depression of vasoconstrictor activity contribute to the development of the vasodilatation during and after the stimulus. The observation of a differential pattern of activation of muscle and renal vasoconstrictor fibres implies a reciprocal influence exerted on these sympathetic outflows by neurones in the defence areas of the brain.

Effect of acetazolamide on exercise performance and muscle mass at high altitude.

The effect of acetazolamide (Az) on exercise performance and muscle mass in acclimatised subjects at an altitude of 4846 m was assessed in 11 subjects and compared with the effect of placebo on 10 other subjects. Exercise performance at 85% maximum heart rate fell by 37% in the Az group and by 45% in controls (p less than 0.05).

Inhibition of sporulation in Bacillus subtilis by bromodeoxyuridine and the effect on DNA replication.

A 5-bromo-2'-deoxyuridine (BUdR)-tolerant derivative of a thymidine (TdR)-requiring strain of Bacillus subtilis was used to examine the effect of BUdR, an analogue of TdR, on sporulation. At a TdR:BUdR ratio which had little effect on growth, sporulation was inhibited if cells were exposed to BUdR during the period of DNA synthesis at the onset of the process. Cells recovered from BUdR inhibition of sporulation if the analogue was removed and DNA replication allowed to continue with TdR alone.

Tolerance to bromodeoxyuridine in a thymidine-requiring strain of Bacillus subtilis.

Mutations which allow tolerance to 5-bromo-2'-deoxyuridine (BUdR) in a thymidine (TdR)-requiring strain of Bacillus subtilis have been examined. Differences in sensitivity to BUdR existed between isogenic strains harbouring the mutations. Those mutations originally isolated as BUdR-tolerant also bestowed tolerance to 5-bromouracil and vice versa.

Noradrenergic projections to the spinal cord and their role in cardiovascular control.

The evidence for the location of spinally projecting noradrenergic neurones in rat, rabbit, cat, monkey and birds is reviewed. It is concluded that these neurones lie in the A7, A6, A5 and A1 groups. There is a selective innervation of the autonomic nuclei of the thoracic cord running ventrolaterally in the medulla and most probably arising from A5 and to a lesser extent from A1.