- Rat heart cells in culture were found to be a unique model for studying biochemical and pharmacological aspects of thiamine deficiency. When thiamine was excluded from the growth medium, the following effects were observed: (1) Morphological examination did not show any difference between control and thiamine-deprived cells during the first 10 days. However, after 10-11 days spontaneous contractions ceased, accompanied by initiation of cell degeneration; (2) Intensive degeneration and cell death were observed after 14-16 days. (3) Thiamine pyrophosphate (TPP) concentration in thiamine-deprived cells was decreased gradually, with an elimination half-life of 4-5 days. (4) [3H]deoxyglucose uptake by the cells was increased, even after 1 day of thiamine deprivation. (5) ATP level decreased after 8 days and reached 50% of control cells after 10 days. (6) In thiamine-deprived cells, thiamine addition caused a 60% rise in contraction amplitude but contraction rate was not altered significantly. (7) All these effects were reversible if thiamine was supplied before the initiation of the degeneration processes.