Changes in Ca-ATPase Activity and Ca Uptake Rate of Heart Muscle SR of the Stroke-Prone SHR in Relation to Aging

Abstract

When Ca uptake in the presence of ATP is referred to as (active plus passive) Ca transports and Ca uptake in the absence of ATP as passive one in microsomal fractions of SHRSP, there is an inverse effect between (active plus passive) Ca transports and passive transports. At 2 or 3 months old, when the hypertensive stage is remarkably progressing, the active Ca transport is lowered while passive one accelerated. Although this present result seems to be partly inconsistent with the Ca-ATPase activity, inverse relationship on Ca uptake in sarcoplasmic reticulum level is well agreement with the result of Ca effect on tonus of rat aortic strips. This observation on hypertensive development would be of interest in view that this Ca uptake rate has been lowered at 2 or 3 months old when hypertensive stage is progressing