DZF-Project Günter Niemeyer

Effects of changes in blood-glucose level on the function of the mammalian retina in vivo and in vitro

G. Niemeyer, M.D., Prof. emeritus

Deptm. of Ophthalmology, Neurophysiology Laboratory, Universitätsspital, 8091 Zurich, Switzerland


Keywords: cat anaesthesia, monitoring respiration, diabetes melliitus, glucose metabolism, in vitro perfusion, electrophysiology

Begin and End of the Project: 1998-2002

Background and Aim

Background: Long-term general intubation-anesthesia is required to modulate the glucose level of cats by either insulin- or glucose infusion to study effects on the retina.

Several apsects of the physiology, metabolism and pharmacology of the mammalian retina can be best or exclusively studied in vitro. Ther perfection of the anesthesia of a given experimental animal and minimization of the number of animals necessary was among our principal goals. The pCO2 meter sponsored by the Doerenkamp-Zbinden Stiftung was a prerequisite to adequately monitor the status and quality of the anesthesia of the cats.(all experiments were approved by Kantonales Tierschutzamt, Zürich)

Aim: To extend our understanding of the  requirements of glucose and oxygen of the mammalian retina ( related to diabetes mellitus, rod –photoreceptor function, cone-photoreceptor function under controlled metabolic conditions)

Methods and Results

In vivo modulation of the glucose level of the anesthetized cat, in vitrio perfusion of mammalian eyes to control hyper – and hopoglycemia for short time spans. Stuidy of effects on the retina with complex and in this laboratory well established electerophysiolgy technology.

Conclusions and Relevance for 3R

The rod system of the mammalian retina is exquisitely sensitive to changes in glucose, whereas the cone- system is much less sensitive. The perfection of our intubation - anesthesia protocol (as confirmed by a University Institution of Bern Switzerland) allowed to optimize and stablilize the conditions of the experimental animal over up to 12 hrs. This result allowed to confine the research to a very small number of animals.