{'fraction_non_alphanumeric': 0.033468559837728194, 'fraction_numerical': 0.02079107505070994, 'mean_word_length': 5.576666666666667, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
VERAPAMIL, PROSTAGLANDINS AND PULMONARY HYPERTENSION

The report by Suggett, Mohammed & Barer (1980) on the effect of angiotensin, hypoxia and verapamil on pulmonary vessels prompts me to add the following. Though hypoxia is known to induce pulmonary vasoconstriction and hypertension, and pulmonary oedema of high altitude which is usually associated with pulmonary hypertension may be due to hypoxia (Das, 1980), the exact mechanism of this is not known. Oxygen is essential for the normal synthesis of vasodilator prostaglandins and hypoxia and hyperoxia enhance the synthesis of vasoconstrictors like prostaglandin FZCY and thromboxane A2 (TXAz), which may be one of the mechanisms responsible for the development of pulmonary hypertension due to high altitude and hypoxia (Das, 1980). This is further supported by our recent finding that verapamil, a calcium antagonist, which is known to inhibit the development of hypoxic pulmonary vasoconstriction (McMurthy, Davidson, Reeves & Grover, 1976) behaves as an antagonist of prostaglandin E (Das, Chainulu & Naik, 1980). Prostaglandin E is believed to regulate the synthesis of prostacyclin (PGIz); that is, as prostaglandin EZ levels fall, prostacyclin levels rise and vice versa (Das & Padma, 1979; Das, 1981). Thus verapamil is likely to enhance prostacyclin levels by its antagonistic action against prostaglandin EZ (Das, 1981; Das & Padma, 1979). Prostacyclin is a powerful vasodilator and anti-aggregator of platelets; hence, whenever prostacyclin levels rise, pulmonary vasodilatation occurs and protects from the development of pulmonary hypertension (Das, 1981). Thus, the beneficial effect of verapamil in hypoxia-induced pulmonary vasoconstriction may be due to its action on the prostanoid system. Hence, verapamil may prove to be of benefit in the management of pulmonary hypertension of the primary type and that due to corpulmonale in which hypoxia may aggregate the pulmonary vascular vasoconstriction.