Suppressive actions of betaxolol on ionic currents in retinal ganglion cells may explain its neuroprotective effects.

@article{Hirooka2000SuppressiveAO,
  title={Suppressive actions of betaxolol on ionic currents in retinal ganglion cells may explain its neuroprotective effects.},
  author={Kazuyuki Hirooka and Melanie E. M. Kelly and William H Baldridge and Steven Barnes},
  journal={Experimental eye research},
  year={2000},
  volume={70 5},
  pages={
          611-21
        }
}
Betaxolol, a beta 1-selective adrenoceptor antagonist, is widely used in the treatment of glaucoma. In addition to its ocular hypotensive effects, betaxolol has been suggested to act as a retinal neuroprotective agent (Osborne et al., 1997). To investigate possible mechanisms underlying the neuroprotective effects, we tested the actions of betaxolol on ion channels and calcium signaling in isolated retinal ganglion cells. Betaxolol (50 microM) reduced by about 20% the high-voltage-activated… 
Effects of β-adrenergic blockers on glutamate-induced calcium signals in adult mouse retinal ganglion cells
TLDR
The data are consistent with previous reports that betaxolol and other β-adrenergic blockers may exert its neuroprotective action by suppression of glutamate-induced intracellular calcium increase in retinal ganglion cells.
The beta-adrenoceptor antagonists metipranolol and timolol are retinal neuroprotectants: comparison with betaxolol.
TLDR
The ability to confer neuroprotection to retinal neurones is a common feature of three ophthalmic beta-adrenoceptor antagonists (betaxolol, metipranolol and timolol), which appears to relate to their capacity to attenuate neuronal calcium and sodium influx.
Comparative effects of antiglaucoma drugs on voltage-dependent calcium channels
TLDR
Of the antiglaucoma drugs investigated, betaxolol displays the greatest L-type VDCC-blocking activity and this may be of clinical relevance, and additional experiments strongly suggested that the effect of betxolol on the NMDA-stimulated 45Ca2+ resulted from inhibition of L- type VD CCs.
Comparison of the neuroprotective effects of adrenoceptor drugs in retinal cell culture and intact retina.
TLDR
Betaxolol reduced glutamate excitotoxicity in retinal neurons in vitro through a mechanism independent of beta-AR interactions, and may be due, at least in part, to a direct reduction of glutamate receptor-mediated increases of [Ca2+]i.
Hypoxia-induced retinal ganglion cell death and the neuroprotective effects of beta-adrenergic antagonists
TLDR
Refined RGC damage induced by hypoxia involves Bax-dependent apoptotic pathway, but mostly independent of glutamate receptor-mediated excitotoxicity, and betaxolol, timolol and nipradilol showed a protective effect against hypoxIA-induced RGC death, which was thought to be irrelevant either to calcium channel or beta-adrenoceptor blocking effects.
Invited review: Neuroprotective properties of certain beta-adrenoceptor antagonists used for the treatment of glaucoma.
  • N. Osborne, J. Wood, G. Chidlow
  • Medicine
    Journal of ocular pharmacology and therapeutics : the official journal of the Association for Ocular Pharmacology and Therapeutics
  • 2005
TLDR
Of the substances used to lower intraocular pressure in glaucoma, beta-blockers have unique additional characteristics that also give them the capacity to act as neuroprotectants.
Protective effects of betaxolol in eyes with kainic acid-induced neuronal death
TLDR
Topically applied betaxolol has neuroprotective effect on the retinal cell damage due to KA-induced neurotoxicity, according to Morphometric analysis of retinal damage in KA injected eyes.
Sigma-1 receptor stimulation attenuates calcium influx through activated L-type Voltage Gated Calcium Channels in purified retinal ganglion cells.
TLDR
Results indicated that σ-1r agonists can inhibit KCl induced calcium ion influx through activated L-type VGCCs in purified RGCs, which is the first report of attenuation of L- type VGCC signaling through the activation of ρ-1rs in purifiedRGCs.
Are there any benefits of Betoptic® S (betaxolol HCl ophthalmic suspension) over other β-blockers in the treatment of glaucoma?
TLDR
Experimental studies have revealed that the drug reaches the retina after topical administration and displays a voltage-dependent L-type calcium channel blocking activity, which probably allows betaxolol to improve retinal perfusion and to serve as a neuroprotective agent recommendable in various forms of glaucoma.
Systemic propranolol reduces b-wave amplitude in the ERG and increases IGF-1 receptor phosphorylation in rat retina.
TLDR
Overall, beta-adrenergic receptor antagonism produced a dysfunctional ERG, which occurred with an increase in IGF-1R phosphorylation and activation of VEGF, which may have detrimental effects on the retina.
...
1
2
3
4
5
...

References

SHOWING 1-10 OF 32 REFERENCES
The relaxant action of betaxolol on isolated bovine retinal microarteries.
TLDR
Since betaxolol has significantly less membrane stabilizing activity than has propranolol, this activity is not responsible for the relaxant action of beta blockers on retinal microarteries.
Retinal ganglion cell dysfunction induced by hypoxia and glutamate: potential neuroprotective effects of beta-blockers.
TLDR
Hypoxia and elevated glutamate levels in the retina may represent a final pathway in diseases affecting retinal ganglion cells, such as glaucoma, and these actions may protect ganglions cells from damage caused by ischemia or raised glutamate levels.
In vivo and in vitro experiments show that betaxolol is a retinal neuroprotective agent
TLDR
The combined data show that betaxolol is a neuroprotective agent and attenuates the effects on the retina induced by raising the intraocular pressure to simulate an ischaemic insult as may occur in glaucoma.
Two Metabotropic γ-Aminobutyric Acid Receptors Differentially Modulate Calcium Currents in Retinal Ganglion Cells
TLDR
This study demonstrates that ganglion cells possess two types of metabotropic GABAB receptor: one sensitive to baclofen and another to cis-aminocrotonic acid (CACA), providing a wide range of neural integration at the final stage of retinal information processing.
Inhibitory action of betaxolol, a β‐selective adrenoceptor antagonist, on voltage‐dependent calcium channels in guinea‐pig artery and vein
TLDR
It is suggested that betaxolol is a unique β‐adrenoceptor antagonist that has a direct inhibitory action on voltage‐dependent Ca2+ channels in vascular smooth muscle cells.
The direct vascular relaxing action of betaxolol, carteolol and timolol in porcine long posterior ciliary artery.
TLDR
The vascular relaxing properties of three beta adrenoceptor antagonists were characterized, compared and contrasted in the porcine long posterior ciliary artery to suggest that this property is much more likely to contribute to any potentially beneficial effects of betaxolol than carteolol or timolol.
Desensitizing glutamate receptors shape excitatory synaptic inputs to tiger salamander retinal ganglion cells
TLDR
Cyclothiazide selectively enhanced the AMPA/KA receptor-mediated component of ganglion cells EPSCs, suggesting that desensitization of AMpa/KA receptors shape transient L-EPSCs.
Betaxolol. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy in hypertension.
TLDR
Betaxolol is an effective alternative to other beta-blocking drugs in patients with essential hypertension, with properties that may offer advantages in some patients, and has been well tolerated in most patients.
A slowly inactivating potassium current truncates spike activity in ganglion cells of the tiger salamander retina
  • P. Lukasiewicz, F. Werblin
  • Biology, Medicine
    The Journal of neuroscience : the official journal of the Society for Neuroscience
  • 1988
TLDR
How the inactivating outward current acts to ensure a graded spiking response and to truncate the spiking output in the presence of large excitatory inputs is analyzed.
Open-channel block of N-methyl-D-aspartate (NMDA) responses by memantine: therapeutic advantage against NMDA receptor-mediated neurotoxicity
TLDR
Low micromolar concentrations of memantine, levels known to be tolerated by patients receiving the drug for the treatment of Parkinson's disease, prevent NMDA receptor-mediated neurotoxicity in cultures of rat cortical and retinal ganglion cell neurons; memantine also appears to be both safe and effective in a rat stroke model, suggesting that memantine has considerable therapeutic potential for the myriad of clinical entities associated with NMda receptor- mediated neurotoxicity.
...
1
2
3
4
...