The Two Factors: Arterial Pressure and Adrenal Secretion
The evidence just presented has shown that splanchnic stimulation improves the contraction of fatigued muscle. Splanchnic stimulation, however, has two effects—it increases general arterial pressure and it also causes a discharge of adrenin from the adrenal glands. The questions now arise—Does splanchnic stimulation produce the improvement in muscular contraction by increasing the arterial blood pressure and thereby flushing the laboring muscles with fresh blood? Or does the adrenin liberated by splanchnic stimulation act itself, specifically, to improve the muscular contraction? Or may the two factors coöperate? These questions will be dealt with in the next two chapters.