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Biomedical subjects

M Nakabayashi

Publications and source records attributed to M Nakabayashi.

92 records · Page 6Linked to original sources
PubMedDate not supplied

Ischemic hypertension of pigeon eye.

PURPOSE: To determine the etiology of open-angle glaucoma in human eyes, we tested the hypothesis that ischemia of the endothelial cells lining Schlemm's canal alters the intraocular pressure (IOP) by affecting the transport of fluids out of the eye. METHODS: Experiments were conducted on pigeons. After blocking the two major arteries to the aqueous sinus artery of one eye by laser photocoagulation, the episcleral arteries of both eyes were cauterized. The IOP was measured with a Mentor pneumatonometer before, immediately, and several days after blocking the major arteries. RESULTS: After the episcleral cauterization, the IOP of the laser-treated eye rose significantly and was maintained for at least 3 hours. By day 2, the IOP had recovered to the pre-cauterization level. The IOP of the control eye remained unchanged throughout the experiment. CONCLUSION: These results strongly support the hypothesis that ischemia of the endothelial cells lining Schlemm's canal plays a role in the control of the IOP.

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PubMedDate not supplied

Anatomical and physiological studies on the aqueous sinus artery of the pigeon eye.

PURPOSE: To test the hypothesis that ischemia of the Schlemm's canal endothelium is involved in the control of intraocular pressure (IOP). METHODS: Experiments were conducted on pigeons. The course of the aqueous sinus and the aqueous sinus artery was determined by examining serial sections and the distribution of polymerized resin in the limbal region of the pigeon eye. Ischemia was produced by blocking two major arteries to the aqueous sinus artery and then determining the effect on the IOP. RESULTS: The anatomy and course of the pigeon aqueous sinus and aqueous sinus artery indicated that they are homologous to the human Schlemm's canal and Schlemm's canal artery, respectively. When the arterial inflow to the aqueous sinus artery was blocked by laser treatment, injected resin was absent in the artery but a small amount invaded the aqueous sinus. Blockage of the two major arteries to the aqueous sinus artery did not alter the IOP. CONCLUSIONS: The similarity of the pigeon aqueous sinus and aqueous sinus artery to the human Schlemm's canal and Schlemm's canal artery indicates that the pigeon eye can be used to study the relationship between ischemia of the endothelial meshwork cells and IOP. The lack of a change in IOP in pigeons after ischemia induction was probably the result of anastomotic arterial blood inflow to the aqueous sinus directly, and thus ischemia was not produced by blocking the two major arteries to the aqueous sinus artery.

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