The pulmonary circulation of normal male subjects has been studied in La Paz (3700 m.) in different conditions:
1. At rest: The pulmonary arterial pressures and resistances are higher than at sea level, but the cardiac index remains similar (mean pulmonary arterial pressure: 21 +- 4mmHg. Cardiac Index: 3,91 +- 1,09 1.min-1 .m-2; pulmonary arteriolar resistances: 148 +- 43 dynes.sec-1 .cm-5).
In the highlanders, the level of the pulmonary arterial hypertension (PAHT) is mainly related to structural factors; on the other hand, lowlanders in La Paz mostly show functional changes in relation to precapillary arteriolar vasoconstriction.
2. During exercise: The physiological PAHT markedly increases in relation to the raise of the cardiac output, and to a precapillary arterial vasoconstriction induced by the…||es_ES