1028 



Krijgsman, B. J., and G. A. Divaris. 1955. 



Contractile and pacemaker mechanisms of the heart of molluscs. Biol. Rev. 

 30(1): 1-39. 



This valuable review paper makes numerous references to Venus but does not 

 give the species. The heart mechanism of mollusks is by no means completely 

 understood, but conclusions can be drawn. The systolic mechanism is 

 situated in muscle fibers of heart wall. These muscles are powerful enough 

 to propel blood through the system, in which capillaries often present 

 considerable resistance. The mechanism of diastole is related to 

 hydrodynamic conditions in pericardial cavity. Contraction of ventricle 

 creates suction, which, through the pericardial fluid, expands the auricles. 

 The pacemaker mechanism is myogenic and diffuse. The basis of myogenic 

 automatism is chemoreception of muscle fibers. Chemical stimulus to heart 

 muscle probably is provided by a metabolite produced by the beating heart. 

 Stretching muscles lowers the threshold for this metabolite. Antagonism 

 between mono- and divalent cations in their action on heart has been 

 demonstrated. The pacemaker system is influenced by extrinsic regulatory 

 nerves: inhibitory fibers which probably are cholinergic, and accelerating 

 fibers which may be adrenergic. Atropine, ergotamine and possibly also 

 eserine act differently on molluscan heart than on hearts of vertebrates. 

 These compounds therefore are not suitable for investigating the contingent 

 neurohumors of molluscan heart. - J.L.M. 



1029 



Krishnaswamy, S., J. E. G. Raymont, and J. Tundisi. 1967. 



Succinic dehydrogenase activity in marine animals. Internatl. Rev. Ges. 

 Hydrobiol. 52(3): 447-451. 



The succinic dehydrogenase complex is an integral part of metabolic oxidative 

 mechanisms in many animals. It has a key role in terminal oxidation of 

 carbohydrates, fats, and amino acids. Its occurrence in marine species had 

 so far received little attention. Porifera, Coelenterata , Mollusca,and 

 Crustacea from southern English waters were studied. Venus mereenaria gill 

 tissue had a mean activity of 7.50 ug/mg/24 hr, with a range of 5.80 to 12.00. 

 This activity was much higher than that of Cavdium or Mytilus, or Carainus, 

 in fact it was higher than that of any other animal studied. The activity was 

 inhibited by sodium malonate, which suggested possible existence of the 

 tricarboxylic acid cycle. - J.L.M. 



1030 



Kritchevsky, David, and Shirley A. Tepper. 1961. 



The free and ester sterol content of various foodstuffs. J. Nutrition 

 74(4): 441-444. 



According to Thompson (1964), abstracted elsewhere in this bibliography, 

 these authors reported 122 mg/100 g total cholesterol in clam meats (species 

 not given). - J.L.M. 



1031 



Krug, Glenn, Jeffrey Lindenbaum, and Yu Chen Lin. 1972. 



The effect of mercenene on the in vitro glucose utilization in Krebs-2 

 carcinoma cells. Proc. Pa. Acad. Sci. 46: 18 (abstract). 



Respiration and glycolysis were used to study utilization of glucose by 

 Krebs-2 carcinoma cells in presence and absence of mercenene (crude aqueous 

 extract of Meraenaria mevaenavia) . No results are given. - J.L.M. 



289 



