Chinese drugs for Shen-tonification could impact the expression of transcription factors in the hypothalamus of aged rats, dominantly on the neuro-endocrine factors responsible for the growth and development. The effects of drugs for tonifying Shen-yang and for tonifying Shen-yin are different, which is probably one of the pharmacological mechanisms of the Shen-tonifying drugs.

Losartan inhibits hyposmotic-induced increase of I Ks current and shortening of action potential duration in guinea pig atrial myocytes Objective: The present study aims to investigate the effect of losartan, an selective angiotensin II type 1 receptor (AT 1 R) blocker, on both the increase of I Ks current and shortening of action potential duration (APD) induced by stretch of atrial myocytes, and to uncover the mechanism underlying the treatment of fibrillation (AF) by AT 1 R blockers. Methods: Hyposmotic solution (Hypo-S) was applied in the guinea pig atrial myocytes to simulate cell stretch, then patch-clamp technique was applied to record the I Ks and APD in atrial myocytes. Results: Hypo-S increased the I Ks by 105.6%, while Hypo-S+1-20 μM of losartan only increased the I Ks by 70.3-75.5% (p<0.05 vs. Hypo-S). Meanwhile, Hypo-S shortened APD 90 by 20.2%, while Hypo-S+1-20 μM of losartan shortened APD 90 by 13.03-14.56% (p<0.05 vs. Hypo-S). Conclusion:The above data indicate that the effect of losartan on the electrophysiological changes induced by stretch of atrial myocytes is associated with blocking of AT 1 receptor, and is beneficial for the treatment of AF that is often accompanied by the expansion of atrial myocytes and the increase of effective refractory period.

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