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B Robertson

Publications and source records attributed to B Robertson.

At least 91 records · Page 5Linked to original sources
PubMed1998

Anterograde transport of horseradish-peroxidase conjugated isolectin B4 from Griffonia simplicifolia I in spinal primary sensory neurons of the rat.

Anterograde transport of the isolectin B4 from Griffonia simplicifolia I (B4) conjugated to horseradish peroxidase (HRP) was investigated in rat somatic and visceral primary sensory neurons at different spinal levels. Injection of B4-HRP into the L5 dorsal root ganglion (DRG) resulted in labelling in the sural nerve, but not in the gastrocnemius nerves. Free nerve endings and lanceolate-like nerve endings were labelled in the lateral hindpaw skin. Labelled fibres were also observed in the greater splanchnic nerve following B4-HRP injection into the T10-11 DRGs. Electron microscopic examination of the labelled nerves showed that B4-HRP labelled exclusively unmyelinated axons. In the spinal cord, labelling was observed in the superficial dorsal horn, and additionally, although much more sparse, in the medial and lateral collateral projections following injections into the T10-11 DRGs. The results suggest that B4-HRP should be a suitable anterograde tracer of unmyelinated cutaneous and splanchnic but not muscle primary afferent fibres.

Animals↗
PubMed1998

Synthetic peptide-containing surfactants--evaluation of transmembrane versus amphipathic helices and surfactant protein C poly-valyl to poly-leucyl substitution.

Pulmonary surfactant contains two hydrophobic proteins, SP-B and SP-C. With the aim of identifying synthetic SP-B and SP-C substitutes for replacement therapy of respiratory distress syndromes, we have studied two transmembrane peptides and two amphipathic peptides that are located in the plane of a phospholipid bilayer. One amphipathic peptide was designed by changing the amino acid sequence, but not the composition or size, of the 21-residue peptide KL4. This peptide, designated KL(2,3) from its spacing of nonpolar and polar residues, exhibited similar alpha-helical content as KL4 but was oriented along a phospholipid bilayer plane, in contrast to the transmembrane orientation of KL4 in the same environment. The second amphipathic peptide analyzed was succinyl-LLEKLLEWLK-amide (WMAP10). KL4 more efficiently accelerated the spreading of a mixture of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (Pam2GroPCho)/phosphatidylglycerol (PtdGro)/palmitic acid (PamOH), 68:22:9 (by mass), at an air/water interface than did any of the amphipathic peptides. Similarly, KL4, but not KL(2,3), when present in an interfacial monolayer composed of Pam2GroPCho/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol, 7:3 (by mass), increased lipid insertion from subphase vesicles. An SP-C analogue, SP-C(Leu), with all helical valyl residues in native SP-C replaced with Leu and the palmitoylcysteines at positions 5 and 6 replaced with Ser, but otherwise with essentially the same primary structure as the native peptide, was analyzed. SP-C(Leu) exhibited similar alpha-helical content as native SP-C and a transmembrane orientation and, in contrast to poly-valyl-containing synthetic peptides, it folds into a helical conformation after acid-induced denaturation. SP-C(Leu) accelerated the spreading of Pam2GroPCho/PtdGro/PamOH, 68:22:9 (by mass), almost identically to native SP-C, and lowered the surface tension during rapid cyclic film compressions in a pulsating bubble surfactometer to near zero and 43 mN/m at minimum and maximum bubble size, respectively. Airway instillation of 2% (by mass) SP-C(Leu) combined with Pam2GroPCho/PtdGro/PamOH in preterm rabbit fetuses improved dynamic lung compliance by about 30% compared with untreated controls.

Animals↗
PubMed1998

Phototransformation and proton pumping activity of the 14-fluoro bacteriorhodopsin derivatives.

The photoinduced behavior and proton pumping characteristics of some bacteriorhodopsin (BR) analogs with fluorinated chromophores (all-trans 14-fluorinated [14-F] retinal and 13-cis 14-F retinal) derived from wild type (WT) and D96N mutant BR were investigated. These analogs were characterized using spectrophotometry and a highly sensitive electrochemical technique. Similar to the white membrane JW2N, the apomembranes WT ET 1000 and D96N form photoactive pigments with the 14-F chromophores. The resulting analogs have a major absorption band at 588 nm. Red-shifted pigment (lambdamax</=680 nm) has been previously observed as a minor component of the major 587-nm pigment in 14-F BR made with white membrane JW2N. A similar red-shifted pigment is formed under yellow light (lambda>500 nm) only in the 14-F analogs derived from WT ET 1000. The measurements of the photoinduced transformation in 14-F WT analogs show that the photocycle of the major pigment occurs simultaneously with the process in the red region and is partially masked by the formation of the red-shifted species. The 14-F D96N samples have a significantly slower and more complicated photoinduced behavior. Electrochemical measurements show that the photoinduced transformation of the red species is not accompanied by proton transport.

Bacteriorhodopsins↗
PubMed1998

Expression of an oscillating interferon-gamma receptor in the suprachiasmatic nuclei.

The suprachiasmatic nuclei serve as the dominant circadian pacemaker in the mammalian brain, regulating daily behavioral, physiological and hormonal rhythms. In the ventrolateral parts of these nuclei, the receptor for the key immunoregulatory molecule interferon-gamma (IFN-gamma) was detected in the rat brain. The cellular localization of the IFN-gamma receptor corresponded to neuronal elements. Expression of the receptor followed a diurnal rhythm with a peak at zeitgeber time 15. This peak coincided with an enhanced expression of janus kinase 1 and 2 as well as the signal transducer and activator of transcription 1, which constitute the main intracellular signaling pathway of IFN-gamma. This is the first study to show expression of the receptor of an immune modulatory molecule in the pacemaker of the biological clock, which, thus, may be influenced by immune system signal molecules.

Animals↗
PubMed1998

Patch-clamp recordings from cerebellar basket cell bodies and their presynaptic terminals reveal an asymmetric distribution of voltage-gated potassium channels.

Cerebellar basket cells form highly specialized inhibitory synaptic contacts with Purkinje cells, namely the pericellular basket and pinceau nerve terminal structures, wrapping around the Purkinje cell somatic and axon hillock regions. These inhibitory synaptic contacts are ideally located to control the ultimate output of the cerebellar cortex. Previous immunohistochemical studies have shown that these synaptic structures possess a very high density of the dendrotoxin (DTX)-sensitive potassium channel subunit, Kv1.2. We have taken advantage of this unique anatomical arrangement offering a high concentration of identified Kv channel subunits by combining whole-cell patch-clamp recording and fluorescence microscopy to establish a novel preparation and perform the first recordings from unambiguously identified mammalian CNS inhibitory presynaptic terminals. We report that DTX-sensitive potassium channels are present in basket cell terminals but not in the basket cell soma. This selective cellular distribution suggests that these channels play an important role in modulating cerebellar inhibitory synaptic transmission.

Animals↗
PubMed1998

Comparison of rapid bolus instillation with simplified slow administration of surfactant in lung lavaged rats.

The aim of this study was to compare the effects of modified porcine surfactant (Curosurf) given either by a simplified slow delivery technique or by the standard bolus method, on pulmonary gas exchange, lung mechanics, and surfactant distribution in rats with respiratory failure produced by lung lavage. Twelve rats with respiratory failure induced by lung lavage received 200 mg x kg(-1) body weight (b.w.) of tagged porcine surfactant, either by the standard bolus delivery technique or by a simplified 1-min intratracheal infusion method, not requiring interruption of mechanical ventilation. Cardiovascular parameters, arterial blood gases, and pulmonary mechanics were measured repeatedly. Surfactant distribution was also measured by dye-tagged microbead spheres. After surfactant administration, there were no overall major differences between groups in mean heart rate, blood pressure, arterial blood gases, dynamic lung compliance, respiratory system resistance, and pulmonary distribution of exogenous surfactant. However, after 180 min pulmonary gas exchange was better and compliance higher in the bolus than the 1-min infusion group. A transient decrease in blood pressure and heart rate was observed in the bolus group; this side effect was not seen in animals treated with the simplified 1-min infusion method. We conclude that in rats subjected to lung lavage, the infusion of porcine surfactant by a simplified 1-min procedure produced similar short-term effects compared to the same dose of surfactant given by the bolus method. We speculate that tracheal bolus dosing is highly effective and might be the preferable delivery method for porcine surfactant. Dosing by the simplified method described appears less effective, but since no significant differences were observed, and since it produced less acute adverse effects, it could be used when clinical circumstances preclude rapid delivery.

Animals↗
PubMed1998

Lung function and bacterial proliferation in experimental neonatal pneumonia in ventilated rabbits exposed to monoclonal antibody to surfactant protein A.

Surfactant protein A (SP-A) increases the resistance of surfactant to inhibition by plasma and other proteins. In a previous study we found that a monoclonal anti-SP-A antibody (R 5) increased the sensitivity of surfactant to inhibition by fibrinogen in vivo and in vitro. SP-A has been shown to stimulate microbial phagocytosis and killing by alveolar macrophages. We hypothesized that using R 5 to inactivate SP-A in an animal model mimicking congenital group B streptococcal (GBS) pneumonia might result in increased bacterial proliferation and a deterioration in lung function. Newborn near term rabbits were delivered by Cesarean section, anesthetized, tracheotomized, and ventilated for 5 h in a plethysmograph system allowing measurement of dynamic lung-thorax compliance. Postnatally the animals received one intratracheal injection (5 ml/kg) of R 5, nonspecific IgG, or normal saline. At 30 min all animals received a standard dose of an encapsulated GBS strain by intratracheal injection. The number of bacteria (mean log10 CFU/g lung +/- S.D.; CFU = colony forming unit) was evaluated in lung homogenates. Histologic lung sections were judged by light microscopy. Bacterial proliferation was similar in rabbits treated with the monoclonal antibody (9.33 +/- 0.39; n = 14) and in control animals receiving saline (9.16 +/- 0.35; n = 14) or nonspecific IgG (9.26 +/- 0.31; n = 11). No significant differences were noted on the histologic analysis or in measurements of lung function. We conclude that intratracheal instillation of a monoclonal anti-SP-A antibody did not increase bacterial proliferation in GBS-infected newborn rabbits. These findings suggest that SP-A does not play an important role in protection against encapsulated GBS strains in the neonatal period.

Animals↗
PubMed1998

Interferon-gamma receptors are expressed at synapses in the rat superficial dorsal horn and lateral spinal nucleus.

Interferon-gamma can facilitate the spinal nociceptive flexor reflex and may elicit neuropathic pain-related behavior in rats and mice. Immunoreactivity for the interferon-gamma receptor (IFN-gamma R) occurs in the superficial layers of the dorsal horn and the lateral spinal nucleus in the rat and mouse spinal cord, as well as in subsets of neurons in the dorsal root ganglia. The aim of the present study was to examine the cellular localization and origin of the IFN-gamma R in the spinal cord. As viewed by confocal microscopy, the immunopositivity for the IFN-gamma R was co-localized with that of the presynaptic marker synaptophysin and with neuronal nitric oxide synthase in the lateral spinal nucleus, whereas only a minor overlap with these molecules was observed in laminae I and II of the dorsal horn. There was no co-localization of the IFN-gamma R with markers for astrocytes and microglial cells. Ultrastructurally, the IFN-gamma R was found predominantly in axon terminals in the lateral spinal nucleus, but at postsynaptic sites in dendrites in laminae I and II. The IFN-gamma R expressed in neurons in dorsal root ganglia was transported in axons both centrally and peripherally. Hemisection of the spinal cord caused no reduction in immunolabelling of the IFN-gamma R in the dorsal horn or the lateral spinal nucleus. Since rhizotomy does not affect the immunolabelling in the lateral spinal nucleus, our observation indicates that the presynaptic receptors in this nucleus are derived from intrinsic neurons. The localization of the IFN-gamma R in the spinal cord differed from that of the AMPA glutamate receptor subunits 2 and 3 and the substance P receptor (NK1). Our results, showing localization of IFN-gamma R to pre- and postsynaptic sites in the dorsal horn and lateral spinal nucleus indicate that IFN-gamma can modulate nociception at the spinal cord level.

Animals↗
PubMed1998

Modulation of inhibitory post-synaptic currents (IPSCs) in mouse cerebellar Purkinje and basket cells by snake and scorpion toxin K+ channel blockers.

Using an in vitro mouse cerebellar slice preparation and whole-cell electrophysiological recording techniques we have characterized Purkinje and basket cell inhibitory post-synaptic currents (IPSCs), and examined the effects of a number of selective peptidergic K+ channel blockers. Spontaneous IPSC amplitude ranged from approximately 10 pA up to approximately 3 nA for both cell types [mean values: Purkinje cells -122.8+/-20.0 pA (n = 24 cells); basket cells -154.8+/-15.9 pA (n = 26 cells)]. Frequency varied from approximately 3 up to approximately 40 Hz, [mean values: basket cells 14.9+/-1.7 Hz (n=26 cells); Purkinje cells 17.9+/-2.2 Hz (n=24 cells)]. 5 microM bicuculline eliminated virtually all spontaneous currents. IPSC rise times were fast (approximately 0.6 ms) and the decay phase was best fit with the sum of two exponential functions (tau1 and tau2: approximately 4 ms and approximately 20 ms, n=40; for both cell types). The snake toxins alpha-dendrotoxin (alpha-DTX) and toxin K greatly enhanced IPSC frequency and amplitude in both cell types; the closely related homologues toxin I and gamma-dendrotoxin (gamma-DTX) produced only marginal enhancements (all at 200 nM). Two scorpion toxins, margatoxin (MgTX) and agitoxin-2 (AgTX-2) had only minor effects on IPSC frequency or amplitude (both at 10 nM). Low concentrations of tetraethylammonium (TEA; 200 microM) had no overall effect on cerebellar IPSCs, whilst higher concentrations (10 mM) increased both the frequency and amplitude. The results suggest that native K+ channels, containing Kv1.1 and Kv1.2 channel subunits, play an influential role in controlling GABAergic inhibitory transmission from cerebellar basket cells.

Animals↗
PubMed1998

Palatal fractures: classification, patterns, and treatment with rigid internal fixation.

A classification of palatal fracture types is developed from patterns observed on CT scans, and success with open reduction techniques is correlated with fracture pattern. The six palatal fracture types are as follows: I, anterior and posterolateral alveolar; II, sagittal; III, parasagittal; IV, para-alveolar; V, complex; and VI, transverse. Associated fractures were LeFort I (100 percent), LeFort II and III (55 percent), mandible (48 percent), and dental (55 percent). Large segment, sagittally oriented palatal fractures could be stabilized with rigid internal fixation. Complete rigid fixation of the palate consists of (1) roof of mouth, (2) pyriform or alveolar, and (3) four LeFort I buttress stabilization. Comminuted palatal fractures were managed by standard LeFort I and alveolar buttress fixation, palatal splinting, and intermaxillary, fixation. If complete rigid fixation was employed in the palate in type II, III, and IV fractures, a palatal splint was avoided in 60 percent of these cases. Rigid internal fixation is therefore concluded to facilitate the treatment of certain types of palatal fractures by reduced length of intermaxillary fixation and avoidance of palatal splinting.

Alveolar Process↗
PubMed1998

Blindness as a complication of Le Fort osteotomies: role of atypical fracture patterns and distortion of the optic canal.

Blindness in patients suffering maxillofacial trauma is usually caused by optic nerve or optic canal injuries. It is, however, an uncommon complication of facial trauma, with a reported incidence of only 3 to 5 percent. This incidence drops dramatically when fractures are performed in the controlled situation of orthognathic surgery. Given the rarity of ophthalmic complications after traumatic Le Fort I injuries, it is not surprising that few cases have been reported after orthognathic surgery. In this article, three cases of visual loss or skull base injury after elective Le Fort I osteotomy are described. All of these cases were presumably straightforward surgically and were performed by experienced surgeons. The literature is reviewed and the pathomechanics of each injury are experimentally explored in a cadaver model. To determine the presence of increased pressure on the optic nerve, optic canal deformation, or fractures extending to the skull base, two separate experiments were devised. In the first experiment, a pressure transduction system was used to document any significant forces that may be directly transmitted to the contents of the optic canal during pterygomaxillary separation. Then tested was the hypothesis that a stepped or tapered osteotomy will allow for a more predictable pterygomaxillary fracture. One of five cadaver specimens in group 1 demonstrated a transient increase in the right optic canal pressure during down-fracture of the maxilla. This change was less than 10 mmHg, and its duration was less than 5 seconds. The canal pressure returned to baseline with the completion of the fracture. In group 2, there was no documented pressure change with either osteotomy technique. Of note, in group 2, all specimens undergoing standard Le Fort osteotomy demonstrated uncontrolled propagation of the fracture lines superiorly in the pterygoid bones. The uncontrolled and unpredictable nature of pterygomaxillary disjunction may result in the extension of fractures to the skull base or the generation of deforming forces to the optic canal may compress or injure the optic nerve and its circulation. It is proposed that a stepped or tapered osteotomy will generate a more controlled pterygomaxillary separation during orthognathic surgery and may reduce the risk of devastating ophthalmologic complications.

Adolescent↗
PubMed1998

Blindness after reduction of facial fractures.

Blindness in patients suffering maxillofacial trauma is usually caused by optic nerve or optic canal injuries. It is, however, an uncommon complication of facial trauma, with a reported incidence of only 2 to 5 percent. Blindness may also follow surgical repair of facial fractures. Many mechanisms, such as intraoperative direct nerve injury, retinal arteriolar occlusion associated with orbital edema, or delayed presentation of indirect optic nerve injury sustained at the time of the initial trauma, have been implicated in causing this blindness. In this article, four cases of visual loss after surgical repair of facial trauma are reported. In a review of the University of Maryland Shock Trauma experience with facial trauma over 11 years, we discovered that 2987 of the 29,474 admitted patients (10.1 percent) sustained facial fractures, and that 1338 of these fractures (44.8 percent) involved one or both of the orbits. One thousand two hundred forty of these patients underwent operative repair of their facial fractures. Three patients experienced postoperative complications that resulted in blindness, a total incidence of only 0.242 percent. Postoperative ophthalmic complications seem to be primarily mediated by indirect injury to the optic nerve and its surrounding structures. The most frequent cause of postoperative visual loss is an increase in intraorbital pressure in the optic canal. When our data were added to the summarized cases, blindness was attributable to intraorbital hemorrhage in 13 of 27 cases (48 percent). In addition, 5 cases in our review attribute the visual loss to unspecified mechanisms of increased intraorbital pressure, bringing the total cases of visual loss caused by intraorbital pressure or hemorrhage to 18 of 27 cases, or 67 percent. Within the restricted confines of the optic canal, even small changes in pressure potentially may cause ischemic optic nerve injury.

Accidents, Traffic↗
PubMed1998

Synthetic surfactant protein analogues.

Surfactant preparations for the treatment of respiratory distress syndrome (RDS) that contain phospholipids and small amounts of the two hydrophobic proteins, SP-B and SP-C, are presently obtained from animal lungs. Since structural information about SP-B and SP-C is available, it appears possible to design analogues that can replace the native proteins in synthetic surfactants. SP-C contains a single helix, but analogues with the poly-Val sequence of the native molecule do not fold into a native-like alpha-helical conformation. However, replacement of all Val with Leu yields efficient folding into a helical structure and Leu-based SP-C analogues effectively accelerate spreading of surfactant lipids and exhibit some physiological activity in animal models of RDS. The inferior in vivo activity of synthetic surfactants containing SP-C only compared to that of surfactant preparations derived from natural sources may be caused by a lack of covalently linked palmitoyl groups in the analogues and/or absence of SP-B. SP-B is significantly larger than SP-C and has a tertiary fold of several amphipathic helices in a dimeric structure. A single simplified amphipathic helical peptide containing only Leu and Lys does not mimic the surface properties of SP-B in vitro. These circumstances make the design of SP-B analogues from solely structural considerations less likely to be successful than in the case of SP-C.

Drug Design↗
PubMed1998

Combined surfactant therapy and inhaled nitric oxide in rabbits with oleic acid-induced acute respiratory distress syndrome.

Intratracheal administration of surfactant and inhaled nitric oxide (INO) have had variable effects in clinical trials on patients with acute respiratory distress syndrome (ARDS). We hypothesized that combined treatment with exogenous surfactant and INO may have effects in experimental ARDS. After intravenous infusion of oleic acid in adult rabbits and 4-6 h of ventilation, there was more than a 40% reduction in both dynamic compliance (Cdyn) of the respiratory system and functional residual capacity (FRC), a 50% increment of respiratory resistance (Rrs), a 70% reduction in PaO2 /FIO2, and an increase in intrapulmonary shunting (Q S/Q T) from 4.4 to 33.5%. The animals were then allocated to groups receiving (1) neither surfactant nor INO (control), (2) 100 mg/kg of surfactant (S) administered intratracheally, (3) 20 ppm INO (NO), or (4) 100 mg/kg of surfactant and 20 ppm INO (SNO), and subsequently ventilated for 6 h. After the period of ventilation, the animal lungs were used for analysis of disaturated phosphatidylcholine (DSPC) and total proteins (TP) in bronchoalveolar lavage fluid (BALF), and for determination of alveolar volume density (VV). The animals in the control group had the lowest survival rate, and no improvement in lung mechanics and blood oxygenation, whereas those in the S group had a modest but statistically significant improvement in Cdyn, Rrs, PaO2 and FRC, reduced Q S/Q T, lowered minimum surface tension (gammamin) of BALF, and increased DSPC/ TP and alveolar VV. The NO group had increased PaO2 and reduced Q S/Q T. The SNO group showed improved Cdyn, Rrs, FRC, DSPC/TP, alveolar VV, and gammamin of BALF comparable to the S group, but there was a further increase in survival rate and PaO2, and additional reduction in Q S/Q T and TP in BALF. These results indicate that, in this animal model of ARDS, a combination of surfactant therapy and INO is more effective than either treatment alone.

Administration, Inhalation↗
PubMed1998

Surfactant inactivation and surfactant therapy in acute respiratory distress syndrome (ARDS).

Surfactant dysfunction constitutes an important element in the complex pathophysiology of acute respiratory distress syndrome (ARDS). In this disease, surfactant may become inactivated by plasma proteins leaking into the airspaces as a consequence of increased alveolar permeability. In addition, surfactant proteins may become degraded by proteolytic enzymes or free oxygen radicals released by inflammatory cells recruited to the airspaces. Regardless of the mechanism involved, surfactant inactivation or degradation may be counterbalanced by increasing the pool of surfactant in the airspaces, i.e., by replacement therapy. Surfactant therapy has been tested with promising results in animal models of ARDS triggered by, e.g., lung lavage, hyperoxia or exposure to various toxic agents. In general, the response to surfactant treatment depends on the quality of the surfactant, timing of treatment in relation to the degree of lung injury, dosage and mode of administration. Encouraging results have been obtained with modified natural surfactants in clinical pilot studies on patients with ARDS, justifying further evaluation of this therapeutic approach in randomized controlled trials.

Animals↗
PubMed1997

Interferon-gamma receptors in nociceptive pathways: role in neuropathic pain-related behaviour.

Interferon-gamma receptor (IFN-gamma R) immunoreactivity was observed in the superficial dorsal horn and lateral spinal nucleus in rat and mouse spinal cord. Dorsal rhizotomies did not reduce immunoreactivity in the rat. IFN-gamma R distribution overlapped with nitric oxide synthase-1 immunoreactivity. In wild-type mice, intrathecal injections of mouse IFN-gamma evoked biting behaviour, whereas mice with disruption of the functional gene for IFN-gamma R did not respond. Both types of mice had similar withdrawal thresholds to mechanical stimulation and reacted similarly to foot-pad carrageenan injections. In contrast to wild-type mice, IFN-gamma R knock-out mice did not show autotomy after sciatic nerve section. This study demonstrates a functional IFN-gamma R in spinal nociceptive pathways related to neuropathic pain.

Animals↗
PubMed1997

Modification of rat brain Kv1.4 channel gating by association with accessory Kvbeta1.1 and beta2.1 subunits.

We have examined the effects of co-expression of Kvbeta1.1 and Kvbeta2.1 subunits on the gating of rat brain Kv1.4 channels, expressed in Xenopus oocytes. Expression of Kv1.4 subunits alone produced a rapidly inactivating "A" type current, which activated at potentials beyond -60 mV in a solution containing high levels of rubidium. Current activation curves obtained from tail current measurements were fitted with a Boltzmann function, with V1/2 = -47 mV and k = 10 mV. Neither the Kvbeta1.1 nor Kvbeta2.1 subunits altered the voltage dependence of activation. Both subunits accelerated the activation time constant of Kv1.4, without affecting its voltage dependence. Surprisingly, the Kvbeta2.1 subunit, which lacks an N-terminal inactivation domain, was almost as effective as the Kvbeta1.1 subunit in speeding up Kv1.4. Steady-state inactivation of Kv1.4 was unchanged upon co-expression with either Kvbeta1.1 or Kvbeta2.1 subunits. Kv1.4 recovered from inactivation with two time constants; apart from an approximately 50% lengthening of the slow time constant with a high Kvbeta2.1 injection ratio, neither time constant was altered by either the Kvbeta1.1 or Kvbeta2.1 subunits, suggesting little interaction with recovery from C-type inactivation. Clearly, beta subunits have the potential to modify the gating of Kv1.4 channels in the brain more subtly than has been suggested previously.

Animals↗