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B. Tian, P.L. Kaufman; Combined Effects of H–7 and Pilocarpine on Outflow Facility, Pupil Diameter and Accommodation in the Monkey Eye . Invest. Ophthalmol. Vis. Sci. 2006;47(13):218.
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To determine if H–7 will enhance a submaximal Pilo dose–induced increase in outflow facility (OF) and inhibit Pilo–induced miosis in the monkey eye.
OF was determined by 2–level constant pressure perfusion following anterior chamber exchange with 24.5µM phenylephrine (PE) bilaterally, 24.5µM PE+300µM H–7 bilaterally or 24.5µM PE+300µM H–7±2 or 10µM Pilo in opposite eyes in living monkeys. During perfusions, pupil diameter (vernier calipers) and accommodation (coincidence refractometer) were measured in different periods. OF following 2µM Pilo±10µM H–7 was also determined on a different occasion.
OF in the 300µM H–7+10µM Pilo–treated eye was 73% higher than that in the 300µM H–7 only–treated eye (n=6; P<0.05). Accommodation in the former was slightly but significantly greater than that in the latter (2.6 vs. 0.6 D; P<0.05). Pupil diameter in the former was significantly smaller than that in the latter (3.36 vs. 7.64 mm; P<0.02). However, OF in the 300µM H–7+2µM Pilo–treated eye was similar to that in the 300µM H–7 only–treated eye. Accommodation in the former was slightly and insignificantly greater than that in the latter (0.75 vs. –0.45 D; P=NS). Pupil diameter in the former was only slightly smaller than that in the latter (6.77 vs. 7.66 mm; P=NS). 2µM Pilo+10µM H–7 did not increase OF compared to 2µM Pilo alone.
The averaged pupil diameter in the monkey eye following 10µM Pilo+24.5µM PE or 2µM Pilo+24.5µM PE is ∼3 mm or 4.5 mm respectively (Gabelt and Kaufman, JPET, 263:1133, 1992; Kiland et al, EER, 70:603, 2000). Per the previous and/or current data, 300µM H–7 and 10µM Pilo have additive effects on OF, but the former does not inhibit the latter’s induced miosis; 300µM H–7 partially inhibits 2µM Pilo–induced miosis, but 2µM Pilo does not potentiate the 300µM H–7–induced increase in OF. Subthreshold doses of H–7 and Pilo do not have additive effects on OF. The dissociated effects of H–7 on intramuscular Pilo’s pupillary and accommodative actions in a previous study (Tian et al, Arch Ophthalmol., 116:1070, 1998) are most likely due to a pharmacokinetic mechanism.
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