Saline Solutions for Maintaining the Isolated Heart of the House Fly, Musca domestica L.

Abstract

The pH of the hemolymph of larval, pupal, and adult house Hies was determined electrometrically and found to lie 6.78, d.()4 and 6.17, respectively. Osmotic pressures, obtained by a micro-freezing point method, were 6.68, 7.75 and 9.36 atmospheres, respectively. The concentrations of sodium, potassium, and calcium ions were measured spectrophotometrically. Values for sodium in larval, pupal, and adult hemolymph were 57.6, 61.9, and 43.4 milliequivalents per liter, respectively. Corresponding values for potassium were 4.8, 25.4, and 5.4; and for calcium 7.0, 5.3, and 5.8, respectively. Sodium was found to be the least toxic, followed by calcium and then potassium for the isolated hearts of all stages. The most favorable Xa/K ion ratios for maintaining larval, pupal, and adult hearts were 7.1, 30, and 30, respectively. Corresponding K/Ca ion ratios were 1.3, 4.0, and 1.8. Pupal hearts required a higher osmotic pressure than that of the hemolymph. Suitable solutions for maintaining the heats of the larval heart for 24 hours contain 8.54 g. NaCl, 0.36 g. KC1, and 0.39 g. CaCl2 per liter. Corresponding values for the heart of the pupa are 12.84, 0.33, and 0.12; and for the heart of the adult, 14.52, 0.30, and 0.29, respectively. Pupal and adult hearts require 2.5 g. dextrose and 25 ml. 0.04 M phosphate buffer at pH 7.0 per liter.