Contractile Properties of Extracular Muscle in Cats Reared With Monocular Lid Closure and Artificial Squint

Abstract

Kittens were raised with amblyopia by monocular lid suture or esotropia by transection of extraocular muscles in one eye at the age of 2--3 weeks. Isometric contractions in the inferior oblique muscle were recorded at 20 weeks or at adult age, and the results were compared with those of similarly aged cats with normal visual development. The speed of contraction and the fatigue resistance was reduced in the lid sutured animals. In the esotropic cats studied, fatigue resistance was also reduced but the speed of contraction did not change much. It is suggested that the postnatal eye muscle development can be modified by manipulation of the visual input at an early age. Presumably the impaired binocular vision in the lid sutured and esotropic cats reduced the demand for fusion vergences, and this might be reflected in the changes of eye muscle properties. In monocularly lid sutured cats, eye muscle changes were the same on both sides, suggesting that amblyopia per se did not affect eye muscle development.

Contractile properties and histochemistry of extraocular muscle in the pigmented and the albino guinea pig

“…The results of the present study speak strongly in favour of the idea that differences found between normal and Siamese cats depend on functional and not on genetic differences and that they are related to the lack of binocular vision in the Siamese cat. This idea is further supported by findings that cats with aquired binocular difficiences showed changes in eye muscle properties of the same kind as those seen in the Siamese cats, although not as pronounced (Lennerstrand & Hanson 1979).…”

“…The tendon of the muscle was attached to a sensitive strain gauge for isometric tension recording. The activation of the muscle over the nerve with single shocks and trains of pulses and the recording of the tension responses were performed in the same manner as described in our previous studies on eye muscle (Hanson & Lennerstrand 1977;Lennerstrand & Hanson 1979). The measurements o n twitch and tetanic responses have been described elsewhere (Hanson & Lennerstrand 1977), and are summarized in Fig.…”

“…Siamese extraocular muscle contracted slower and fatigued more easily than muscles of pigmented cats. It has also been demonstrated that eye muscle properties of normally pigmented cats 46* with defects of binocular vision, due to monocular lid suture from an early age, are different from those of cats with normal binocularity and similar to the contractile properties of Siamese cats (Lennerstrand & Hanson 1979). Structural correlates to the physiological deviations were demonstrated by means of histochemical techniques (Lennerstrand 1980).…”

Vocal Motor Performance in Birdsong Requires Brain–Body Interaction

“…Neural stimulation is known to drive MYH expression patterns and contraction speed: in rats, neural activity associated with optokinetic and vestibulo-ocular reflexes stimulates MYH13 expression in extraocular muscles (Brueckner et al, 1999; Moncman et al, 2011). In kittens, the earlier described postnatal increase in contraction speed is impeded by impairing binocular vision (Lennerstrand, 1979; Lennerstrand and Hanson, 1979). Likewise, upregulation of MYH13 in rodent extraocular and laryngeal muscles is prevented by visual deprivation or axotomizing the larynx, respectively (Brueckner and Porter, 1998; Shiotani and Flint, 1998; Brueckner et al, 1999), which in addition provides evidence against the hypothesis that a fixed postnatal developmental program controls MYH13 upregulation.…”