Inhibition by imidazole of the increase in intraocular pressure induced by topical prostaglandin E

Pharmacological modification of bradykinin induced breakdown of the blood-brain barrier

Internal carotid artery infusion of bradykinin caused extensive breakdown of the blood-brain barrier to protein as demonstrated by the extravasation of the marker, horseradish peroxidase, into vessel walls and the adjacent parenchyma. Pretreatment of the animals with indomethacin, trifluoperazine, or imidazole significantly reduced the quantity of abnormally permeable vessels as determined by light microscopy. By electron microscopy, it was determined that bradykinin caused an intense increase in the number of pinocytotic vesicles in the permeable segments, but no change in the interendothelial junctions. After imidazole pretreatment, although the extent of the permeability change was markedly reduced, the intensity of pinocytotic activity in the involved areas was not altered.

Pharmacological modification of blood-brain barrier permeability following a cold lesion

The effect of desipramine, imidazole, thioridazine and trifluoperazine on blood-brain barrier (BBB) permeability after a 24 hour cold lesion was studied in rats. Changes in BBB permeability were determined using a quantitative horseradish peroxidase (HRP) assay. The four drugs tested did not alter the quantity of HRP in the cortex of control animals, or in the contralateral cortex of test animals. However, imidazole, desipramine and trifluoperazine significantly reduced the HRP extravasation in and around the cold lesion. Several mechanisms for this effect are suggested; one possible mechanism common to all these drugs is the reduction of increased vesicular transport in cortical vessels adjacent to the cold lesions.

The effect of polyphloretin phosphate on the aqueous flare response to alpha-melanocyte stimulating hormone

The breakdown of the blood aqueous barrier caused by topical prostaglandin E1 (PGE1), prostaglandin E2 (PGE2) or subcutaneous alpha-melanocyte stimulating hormone (alpha-MSH) was quantified by measurements of the aqueous flare seen in the anterior chamber. Polyphloretin phosphate (PPP) administration subcutaneously was found to effectively block the protein leakage caused by all three traumatic stimuli. The same dose of PPP given intravenously inhibited effectively the flare response to PGE1 and alpha-MSH, whereas the effect of PGE2 was only slightly decreased. Significant inhibition by subconjunctival PPP was not achieved for any of the three stimuli. Assuming that PPP is a specific PG-antagonist the present results support the eariler suggestion that PGs take part in the barrier damaging action of alpha-MSH. However, it cannot be excluded that PPP acts on a step subsequent to PG. This step might be common to PGs- and alpha-MSH-effects on the barrier, explaining why PPP inhibits both types of trauma.

Effect of imidazole on renal gluconeogenesis

The metabolic effects of imidazole were tested in rat renal cortex. Imidazole enhanced the activity of renal cortical phosphodiesterase in vitro. Imidazole inhibited glucose production in a dose-dependent fashion from a variety of substrates in the gluconeogenic pathway proximal to the triose phsophates. The stimulation in renal gluconeogenesis resulting from isoproterenol and parathyroid hormone was inhibited by imidazole. These changes correlated with an inhibition of the augmented levels of renal cortical cyclic AMP levels produced by these hormones. These studies indicate that imidazole is an effective activator of phosphodiesterase in intact renal cells and lend further support to the suggestion that the stimulation of renal gluconeogenesis produced by isoproterenol and parathyroid hormone is mediated by a release of cyclic AMP.

Facilitation by imidazole of the aqueous flare response to alpha-melanocyte stimulating hormone

MSH, like traumata to the eye, cause a permeability disturbance in rabbits, with protein leakage into the aqueous. The MSH effect was enormously increased by instillation of imidazole or pilocarpine. The MSH effect seems to engage a different mechanism than the prostaglandin-dependent action of other agents.