Calcium exchange, structure, and function in cultured adult myocardial cells
Cells digested from adult rat heart and cultured for 14 days demonstrate all the structural elements, in mature form, associated with the process of excitation-contraction (EC) coupling. The transverse tubular (TT) system is well developed with an extensive junctional sarcoplasmic reticulum (JSR). In nonphosphate-containing buffer contraction of the cells is lost as rapidly as zero extracellular Ca concentration ((Ca)/sup 0/) solution is applied and a negative contraction staircase is produced on increase of stimulation frequency. Structurally and functionally the cells have the characteristics of adult cells in situ. /sup 45/Ca exchange and total /sup 45/Ca measurement in N-2-hydroxyethylpiperazine N'-2-ethanesulfonic acid (HEPES)-buffered perfusate define three components of cellular Ca: 1) a rapidly exchangeable component accounting for 36% of total Ca, 2) a slowly exchangeable component (t/sub 1/2/ 53 min) accounting for 7% total Ca, and 3) the remaining 57% cellular Ca is inexchangeable (demonstrates no significant exchange within 60 min). The slowly exchangeable component can be increased 10-fold within 60 min by addition of phosphate to the perfusate. The Ca distribution and exchange characteristics are little different from those of 3-day cultures of neonatal rat heart previously studied. The results suggest that the cells are representative of adult cells in situ and that both sarcolemmal-bound and sarcoplasmic reticular Ca contribute to the component of Ca that is rapidly exchangeable.
- Research Organization:
- Univ. of California, Los Angeles
- OSTI ID:
- 5432650
- Journal Information:
- Am. J. Physiol.; (United States), Vol. 252:2
- Country of Publication:
- United States
- Language:
- English
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551001* - Physiological Systems- Tracer Techniques