Use of formamide increases the number of detectable inputs to polyneuronally innervated mammalian skeletal muscle
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1Department of Anatomy and Cell Biology, Emory University School of Medicine, Atlanta, GA 30322.
Insights
Formamide reveals greater polyneuronal innervation in neonatal rat muscles than d-tubocurarine during the first week. This difference diminishes as the muscle matures, with both agents showing similar results by the second week.
Area of Science:
- Neuroscience
- Developmental Biology
- Muscle Physiology
Background:
- Polyneuronal innervation, where a single muscle fiber receives input from multiple motor neurons, is crucial for motor control development.
- Understanding the factors influencing the detection of polyneuronal innervation is essential for accurate developmental studies.
- Paralytic agents used in electrophysiological studies can potentially influence the observed extent of innervation.
Purpose of the Study:
- To compare the efficacy of formamide and d-tubocurarine in revealing polyneuronal innervation in neonatal rat lateral gastrocnemius muscle.
- To assess how the choice of paralytic agent affects the measurement of innervation during early postnatal development.
- To determine the developmental trajectory of polyneuronal innervation using different paralytic agents.
Main Methods:
- Intracellular recording techniques were employed in neonatal rat lateral gastrocnemius muscles.
- Experiments utilized both formamide and d-tubocurarine as paralytic agents to reduce muscle activity.
- The extent of polyneuronal innervation was quantified by measuring the number of inputs per muscle cell and the percentage of polyinnervated cells.
Main Results:
- Formamide detected a significantly greater extent of polyneuronal innervation compared to d-tubocurarine during the first postnatal week.
- Both the average number of inputs per muscle cell and the percentage of polyinnervated cells were higher when formamide was used.
- The discrepancy in detected innervation between the two agents decreased over the first postnatal week.
- By the second postnatal week, formamide and d-tubocurarine yielded comparable results for the number of observed inputs.
Conclusions:
- The choice of paralytic agent can influence the assessment of polyneuronal innervation in developing muscles.
- Formamide appears to be more sensitive in detecting polyneuronal innervation during the early stages of postnatal development.
- The developmental decline in polyneuronal innervation proceeds similarly regardless of the agent used after the first postnatal week.
Abstract:
We evaluated the extent of polyneuronal innervation in neonatal rat lateral gastrocnemius muscle with intracellular recording techniques using both formamide and d-tubocurarine as paralytic agents. We detected more polyneuronal innervation during the first postnatal week using formamide than d-tubocurarine. Both the average number of inputs per muscle cell and the percentage of polyinnervated cells were greater when formamide, rather than d-tubocurarine, was used to diminish muscle contraction. The difference in the extent of polyneuronal innervation detected using the two methods declines during the first postnatal week and the number of inputs observed with formamide during the second postnatal week does not differ from that seen with d-tubocurarine.